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VRB vets only Flashcards

1
Q

What is the site of sperm production?

A

The paired testes

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2
Q

What else do the testes produce?

A

Testosterone and other hormones

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3
Q

What are the layers surrounding the testis?

inner to outer

A 
Fibrous capsule- the tunica albuginea
Visceral peritoneum
Parietal peritoneum
Internal fascia
External fascia
Dartos (fibroelastic tissue and smooth muscle)
Skin
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4
Q

Where does spermatogenesis occur?

A

Seminiferous tubules

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5
Q

Where are the rete testis found?

A

The mediastinum

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6
Q

Main role of leydig cells

A

Steroid formation

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7
Q

How do the rete testis penetrate the tunic?

A

Via the efferent ducts

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8
Q

Where does the epididymis empty?

A

The deferent duct, and then up via the spermatic cord

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9
Q

Where do the peritoneal coverings come from?

A

The vaginal process- an out pocket from the abdomen leaving through the inguinal ring

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10
Q

What does the cremaster muscle do?

A

Pulls the testes towards the abdomen

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11
Q

What two ligaments attach to the epididymis?

A

The proper ligament and the ligament of tail

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12
Q

Where does the proper ligament lie?

A

Between the epididymis and the testis

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13
Q

Where does the ligament of tail lie?

A

Between the epididymis and the parietal peritoneum

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14
Q

What is the mesorchium?

A

The visceral peritoneum supporting the testicular vessels and the deferent duct.

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15
Q

What is the mesoductus?

A

The part of the visceral peritoneum that covers the deferent duct

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16
Q

What is the space between the parietal and visceral peritoneum called?

A

The vaginal cavity/ space

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17
Q

Which species has a testicular bursa?

A

Horse- the body of the epididymis is not closely attached to the testis

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18
Q

Open castration

A

Testes are removed enclosed in the parietal peritoneum.

Ligate cord, cut distal to ligature.

May decrease risk of complications

Indicated when testes removed due to disease.

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19
Q

Closed castration

A

Parietal tunic is opened and left behind.

Incise close to visceral peritoneum.

Opens peritoneal cavity.

Simpler dissection than closed.

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20
Q

Restraint for equine castration (standing)

A

Performed under sedation and local analgesia.

Avoids risk and cost of GA

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21
Q

Restraint for equine castration (general anaesthesia)

A

Easier for the surgeon.

Different risks though

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22
Q

Bloodless castration methods (2)

A

Burdizzo clamp:
- Severs testicular blood vessels but not scrotal ones

Elastrator rings:
- Cut off blood to testis and scrotum

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23
Q

Chemical castration (4)

A

GnRH vaccines:

  • GnRH susceptible to antibody in the hypophyseal portal system
  • virtually all GnRH can be bound and neutralised

Chronic progestagen administration:
- suppression of GnRH and LH release

GnRH antagonists:
- Suppress release of gonadotrophins by occupying GnRH receptors

Chronic high dose GnRH agonists:
- In some species, initial hypersection is followed by pituitary dissemination and decrease Gn release

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24
Q

What can elevation of scrotal temperature cause?

A

Inhibition of sperm production

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25
Q

Where in the male reproductive system is there counter current flow?

A

Between the testicular artery and vein

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26
Q

Testicular thermoregulatory mechanisms

A
  • Counter current flow
  • Thin skin
  • Often hairless
  • Copious sweat glands
  • Little subcutaneous fat
  • Pendulous scrotum away from abdominal wall
  • Dartos and cremaster muscles
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27
Q

What is the gubernaculum?

A

A fibromuscular mesenchymal core. It runs between testes and runs through the inguinal ring into scrotum. It shortens and helps to pull the testes ventrally during development. It regresses once the testes exit the abdomen.

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28
Q

What hormones are involved in testicular descent?

A

Testosterone, INSL3 and Mullerian inhibiting substance.

Androgens act on the suspensory ligament, allowing it to elongate.

INSL3 matures and stabilises the gubernaculum.

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29
Q

What is cryptorchidism?

A

Hidden testes- can be uni- or bi-lateral.

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30
Q

Timing of testicular descent in different species

A

Ruminants: mid-gestation

Dog, cat, horse: around parturition

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31
Q

What is weird about testicular descent in rat, mole, hedgehog and bat?

A

The testes can ascend back into the abdomen outside of breeding season and reappear in scrotum during the breeding system.

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32
Q

What is true cryptorchid?

A

Testis on normal route, but incompletely descended.

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33
Q

What is ectopic cryptorchid?

A

Testes in abnormal position.

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34
Q

Inguinal hernia

A
  • Herniation of intestine through the inguinal canal into the scrotum
  • Relatively common in horse and pig
  • A surgical emergency if there is brutal strangulation
  • The testicle on the affected side usually has compromised vascular supply and is generally removed
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35
Q

Indirect inguinal hernia

A

The gut stays within the parietal vaginal tunic

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36
Q

Direct inguinal hernia

A

The gut ruptures the parietal tunic

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37
Q

What is the spermatic cord?

A

Provides connection and suspends the testes from the abdomen.

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38
Q

What makes up the spermatic cord?

A

Parietal vaginal tunic, visceral vaginal tunic, deferent duct, testicular artery and vein, artery of deferent duct, lymphatics, testicular nerve to testis

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39
Q

What are the edges of the deep inguinal canal?

A

The free caudal edge of internal abdominal oblique

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40
Q

What are the edges of the superficial inguinal ring?

A

A slit in external abdominal oblique.

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41
Q

What is the vesicogenital pouch?

A

A fold of peritoneum gives rise to a space between the

genital fold fold and the bladder

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42
Q

What is the rectogenital fold?

A

A layer of peritoneum creates a pouch between the genital fold and the rectum.

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43
Q

Arterial supply to the testes

A

Comes directly from the aorta, close to the renal arteries (testicular or internal spermatic artery).

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44
Q

Where does the testicular vein drain?

A

Directly to the caudal vena cava

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45
Q

What is the pampiniform complex?

A

The tortuous testicular veins (for heat and hormone exchange)

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46
Q

What does the internal iliac artery supply?

A

The deferent duct, the epididymis and anastomoses with the testicular artery.

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47
Q

Testicular innervation

A

Sympathetic nerves from fourth, fifth and sixth lumbar ganglia.

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48
Q

Innervation and blood supply of the scrotum

A

Blood supplied by the external pudendal artery and vein. Innervated by the genitofemoral nerve and the perineal branch of the pudendal nerve.

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49
Q

The ampulla

A

Not really an accessory gland as it isn’t a distinct structure. The thickened terminal wall of the vas deferens. It has very glandular walls causing an increase in diameter but not in lumen.

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50
Q

The seminal vesicles

A

Paired structures located dorsolateral to the neck of the bladder. They secrete an alkaline fluid, rich in fructose and usually open into the vas deferens, but into the urethra in the boar.

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51
Q

The prostate gland

A

The only accessory gland present in all domestic species. Its secretions assist in providing the optimum environment for sperm survival and motility. It surrounds the urethra distal to the entry of the vasa deferentia and discharges through many small ducts.

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52
Q

Bulbourethral glands

A

Found in the dorsocaudal aspect of the proximal urethra. They produce a mucous secretion that has a buffering effect and they open into urethra on its dorsal aspect.

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53
Q

What male accessory sex glands do horses have?

A
  • Prominent ampulla
  • Bladder like sacs of seminal vesicles
  • Two lobes of prostate gland joined by isthmus
  • Bulbourethral gland that discharges through multiple pores

(all)

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54
Q

What male accessory sex glands do bulls and rams have?

A
  • Ampulla
  • Large, lobulated seminal vesicles
  • Prostate that surrounds urethra
  • Relatively small bulbourethral gland
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55
Q

What male accessory sex glands do boars have?

A
  • No ampulla
  • Very large seminal vesicles
  • Small, irregular prostate gland
  • Very large bulbourethral gland
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56
Q

What male accessory sex glands do dogs have?

A
  • No ampulla
  • No seminal vesicles
  • Bilobed prostate
  • No bulbourethral gland
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57
Q

What male accessory sex glands do cats have?

A
  • No ampulla
  • No seminal vesicles
  • Prostate surrounds urethra and distal vasa deferentia
  • Present bulbourethral gland
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58
Q

Three parts of the penis

A

The root, the body and the glans

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59
Q

The two types of penis in domestic animals:

A

The musculocavernous penis:

  • Horse and carnivores
  • Low connective tissue content (flaccid when not erect)
  • Engorgement of the erectile tissue with blood leads to an increase in size and stiffening

The fibroelastic penis:

  • Boar and ruminants
  • High connective tissue content and so always firm
  • Increase in length without changes in diameter, occurs due to straightening of the sigmoid flexure
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60
Q

Glans species differences- horse

A

Horse (use diagrams): Dorsal process, collum glandis, corona glandis, urethral sinus, fossa glandis, urethral process, inner and outer prepuce

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61
Q

Glans species variation- bull

A

Flattened dorsoventrally, pointed and twisted.
External urethral orifice is quite narrow.
Lies at the end of a urethral process which is fused with the galea glandis.

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62
Q

Glans species differences- ram

A

Urethral process (sort of hooked), glea glandis, corona glandis, raph glandis.

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63
Q

Glans species differences- boar

A

Spiral shaped

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64
Q

Glans species differences- cat

A

Backward pointing barbs

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65
Q

Glans species differences- dog

A

Rounded, enlarged bulbus glandis and very long cylindrical pars longa

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66
Q

Corpus cavernosum

A

Consists of paired erectile structures with large venous spaces. It is divided by a septum in carnivores but essentially a single compartment as the septum is incomplete. It divides in the root to form the crura.

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67
Q

Corpus spongiosum

A

A tubular erectile structure surrounding the urethra. It expands to for both the glans and the bulb of the penis. Function seems to be to prevent the urethra closing under the pressure of the corpus cavernosum.

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68
Q

Tunica albuginea (penis)

A

The fibroelastic sheath. Trabeculae of connective tissue radiate inwards from it to support the vascular spaces.

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69
Q

The root of the penis

A

Comprises the bulb and the crura.
Crura: separate, proximal portions of the corpus cavernosum
Bulb: broad proximal portion of the corpus spongiosum.

Here the ischio-cavernosus muscle encloses the crura.
The penis is attached to the ischial arch by the crura. The urethra passes over the ischial arch between the crura and then curves forward.

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70
Q

Body of the penis

A

Section between the junction of the crura and the glans. Attached to the pelvic symphysis at its base by the suspensory ligament of the penis.

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71
Q

Glans penis

A

The distal end of penis. It’s erectile tissue derived from the corpus spongiosum. It shows considerable inter-species variation.

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72
Q

Os penis (baculum)

A

Found in the penis of carnivores, and the majority of mammals. (Dog, cat and rat out of domestics).
In the og the ventral surface has a groove for the urethra.

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73
Q

The prepuce (sheath)

A

Forms a cutaneous sheath over the penis. Inner lamina is continuous with the skin of the glans. The prepucial orifice is the external opening of the prepuce.

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74
Q

Equine prepuce

A

Double prepuce- due to degree of lengthening of the penis on erection. Clinical relevance in testing for STI Contagious Equine Metritis.

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75
Q

Ischio-cavernosus

A

O: tuber ischia and adjacent sacrosciatic ligament
I: crus and adjacent body of penis

Encloses the crus and lies within a depression in the semimembranosus muscle. Pulls the penis against the pelvis compressing its dorsal veins and so assists in producing and maintaining erection.

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76
Q

Retractor penis

A

O: continuation of the suspensory ligaments of the anus (attached to the external anal sphincter)
I: Tunica albuginea near glans

Composed of smooth muscle, its action is to withdraw the penis into the sheath after erection or protrusion.

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77
Q

Urethral muscle

A

Found around the pelvic part of the urethra (not actually a penis muscle). Its forceful contraction is important in ejaculation and it also has a role in voiding the last of the urine in micturition.

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78
Q

Bulbocavernosus muscle

A

A continuation of the urethral muscle around the extra-pelvic portion of the urethra. It varies in its degree of extension between species. Its contraction empties the urethra.

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79
Q

Ischio-urethral muscle

A

In the horse, it arises on the crus and ischial arch, passes forward to the urethral muscle.

In the dog, it arises on the tuber ischii and ends on a fibrous ring on the pelvic symphysis, encircling dorsal veins of penis. It is formed of small bands that may assist erection by pressing on the dorsal veins of the penis.

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80
Q

Blood supply to the penis

A
  1. Internal pudendal artery supplies the artery of the bulb of the penis
  2. Internal pudendal also supplies deep artery of the penis
  3. External pudendal artery supplies the dorsal artery of the penis

Veins form rich plexus dorsally and laterally on the penis and drain via the external and internal pudendal veins.

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81
Q

Testicular artery

A

A branch of abdominal aorta, close to kidney.

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82
Q

Innervation of the penis

A

Derived from the pudendal nerves and pelvic sympathetic plexus. The parasympathetic NS is responsible for erection and the sympathetic for ejaculation.

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83
Q

Innervation of the scrotum

A

Genitofemoral n. and the perineal branch of the pudendal n.

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84
Q

Innervation of prepuce

A

Mainly genitofemoral n. with the dorsal nerve of penis from the pudendal n. supplying the penis and also a little skin at the distal extremity.

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85
Q

Innervation of testes

A

Sympathetic nn. from L4-6, entering with testicular artery; dartos muscle supplied from superficial perineal nerve.

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86
Q

Formation of gonads (origins)

A

Form in sublumbar region from intermediate mesoderm

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87
Q

Where do the wolffian ducts

A

Form from urinary ducts of mesonephros

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88
Q

Ovary structure

A

Similar in all mammals

  • Outer peritoneal coating
  • Fibrous tunica albuginea (thinner than in testes)
  • Cortex: follicles and their derivatives (oocytes, granulosa, theca and luteal cells); interstitial cells; stroma
  • Medulla/ hilus: connective tissue, nerves, vasculature, lymphatics
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89
Q

Ovary- species variation

A

General shape dominated by how many in a litter
Sow: mulberry ovary (multilobar) to produce around 16 eggs
Mare: Ovary is ‘inside out’, cortex is inside the medulla. Ovulation is always form the medial ‘ovulation fossa’ towards which maturing follicles migrate.

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90
Q

5 parts of the oviduct

A
  1. Fimbrae (some species)
  2. Infundibulum
  3. Ampulla
  4. Isthmus
  5. Intramural section
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91
Q

Fimbrae of oviduct (some species)

A

Slightly mobile fingers that are involved in grasping newly ovulated cumulus-oocyte complexes. Not a big feature in the domestic species.

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92
Q

Infundibulum of the oviduct

A

Cone like entrance to oviduct

93
Q

Ampulla of oviduct

A

About first 1/2 of oviduct, thin muscle, very folded epithelium

94
Q

Isthmus of oviduct

A

Thick muscular layer, fertilisation occurs around ampulla/ isthmus junction

95
Q

Intramural section of oviduct

A

Where it passes through the uterine wall

96
Q

Four layers of the oviduct

A
  • Serosa/ visceral peritoneum
  • Muscularis (outer longitudinal, inner circular)
  • Submucosa
  • Epithelium- columnar, secretory, ciliated
97
Q

Varied location and structure of female internal structures

A

Carnivore: long horns, simple long cervix, so ovaries up near kidney

Horse: Short horns, simple short cervix, large, indented ovaries close to ilium.

Pig: very long horns, cervical caruncles, ovaries more ventrally

Ruminant: Rams horn shape, cervical rings, uterine caruncles

98
Q

Differential morphologies of the uterus

A

Duplex (rabbit): no fusion at all
Bicornis (most domestic animals) central uterine body/ fused
Simplex (humans): no uterine horns- all fused

99
Q

Uterine structure

A

Much of the epithelium (endometrium) is glandular, the muscularis is complex

100
Q

Uterus specialisations of ruminants

A

Specialised sites for attachment of the embryo: the caruncles- non-glandular protuberances- are often highly pigmented.

101
Q

Canine pro-oestrus

A

Uterus leaks blood by diapedesis (not menstruation)

102
Q

Uterine prolapse

A

Most often seen in ruminants, usually after birth. Entire uterus turns inside out and so hangs out.
Treat by putting osmotic sugar solution on to make it contract down, and push back in

103
Q

Cervix

A

Muscular, fibrous, mucus secreting.

Uterus sealing, sperm storage (?), ferguson reflex at birth

104
Q

Differential cervical structure

A

Mare: often slightly open

Carnivore: Longer, less open

Ruminant: rings

Sow: cervical caruncles

105
Q

Vaginal structure

A

Dual embryology:

  • Cranial is fused Mullerian ducts (meso-)
  • Caudal is canalised sinovaginal bulb (endo-)
  • Cranial is covered by serosa
  • Caudal is retroperitoneal
  • Cow laproscopy via less vascular craniodorsal wall
  • Needs to be physically resilient for copulation
  • Stratified squamous, with Bartholin’s glands
  • Non-sterile, with normal flora
  • Secretes pheremones
  • Orgasm related to sperm propulsion?
106
Q

Vagina and vestibule

A

Cervix: Porto vaginalis, fornix (not pigs)
Vagina: Hymen (separates from vestibule)
Vestibule: Urethral meatus, suburethral diverticulum (ruminants and pigs), rima vulvae

107
Q

Suspensions of the female reproductive tract

A

Rectum: mesorectum, produces the pararectal fossa
Uterus: Broad ligament- a double fold of peritoneum with blood vessels, nerves and smooth muscle, the two horns are held together by the intercornual ligament
Bladder: Lateral vesical ligaments and ventral vesical ligament (urachus)

108
Q

Three parts of the broad ligament

A

Mesovarium= suspensory ligament (elastic in cats)

Mesosalpinx

Mesometrium

109
Q

Round ligament

A

Ventral broad ligament –> ?inguinal canal

persists in some species but not others

110
Q

Ovarian bursa

A

In some species there is a fold of peritoneum between the mesovarium and mesosalpinx.

Present in pigs and ruminants, not really seen in horses. May be partial (carnivores), or completely enclose the ovary (mice).

111
Q

Arteries to the internal female reproductive structures

A

(Utero)ovarian artery- from aorta or renal artery

Anastamoses up the uterine horns

(Middle) uterine artery- from vesical or ext. iliac (largest in ruminants ‘fremitus’, absent in carnivores)

Vaginal/ caudal uterine artery- from urogenital artery

112
Q

Innervation of internal female reproductive structures

A

Parasympathetic supply via pelvic nn.; sympathetic in broad ligaments from hypogastric nn.

113
Q

The four mammalian fetal membranes

A

Yolk sac, allantois, amnion and chorion/ trophoblast

114
Q

Where does the haemotrophic placental exchange occur?

A

Wherever the yolk sac OR allantois contact the trophoblast

115
Q

Mammalian differences in placenta

A

In most marsupials, the yolk sac + trophoblast ‘choriovitelline’ placenta is the most important.

In some eutherians (e.g. ruminants) only an allantois + trophoblast ‘chorioallantoic’ placenta forms.

In other eutherians (e.g. horses) an initial choriovitelline placenta is replaced by chorioallantoic one.

In other eutherians (e.g. mice), both placentas may persist and function until birth.

In all eutherians, the chorioallantoic is the most important (or only) placenta during most of pregnancy.

116
Q

Fetal membrane connections to gut

A
  1. Yolk sac connects to endoderm of midgut (often disappears early)
  2. Allantois connects with endoderm of bladder via urachus- may remain patent e.g. foals
  3. Buccal plate breaks down –> mouth opens into amniotic cavity
117
Q

Fetal shunts in circulation

A

Two R–>L shunts in heart:
Foramen ovale RA–>LA
Ductus arteriosus PA–>Aorta

Umbilical vv. (oxygenated)–> HPV –> through liver as ductus venosus –> CdVC –> right atrium

Iliacs –> vesical (bladder) aa. –> umbilical aa. (deoxygenated)

118
Q

Different types of twins

A

Dizygotic ‘fraternal’: as different as normal siblings

Monozygotic ‘identical’:

  • Dichorionic, diamniotic
  • Monochorionic, diamniotic
  • Monochorionic, monoamniotic (could be conjoined)
119
Q

Placental types- membranes

A
  • Choriovitelline (chorion + yolk sac): some reptiles and most marsupials
  • Choriovitelline, then chorioallantoic: horse, carnivores, rodents (yolk sac persists)
  • Chorioallantoic: some reptiles, ruminants, pigs
120
Q

Placental types- shape

A
  • Discoid: humans and rodents
  • Cotyledonary: ruminants
  • Zonary: carnivores
  • Diffuse: equids, pigs
121
Q

Placental types- implantation

A
  • Central ‘superficial’: ungulates
  • Eccentric: carnivores, rodents
  • Interstitial ‘invasive’: humans
122
Q

Placental types- cell layers

A
  • Epitheliochorial: ungulates, prosimians (6 layers)
  • Endothelialchorial: carnivores, pinipeds (4 layers)
  • Haemochorial: simians, rodents, lagomorphs, insectivores
123
Q

Placental types- surface area

A
  • Folded: pig
  • Lamellar: carnivores
  • Villous + crypts: equids, ruminants, humans, rodents
124
Q

Placental types- dehiscence

A
  • Non-deciduate: domestic animals
  • Deciduate: humans
  • Contra-deciduate: moles
125
Q

Placental types- relative capillary flow

A
  • Counter-current: horse, rabbit (efficient)

- Cross-current: ruminants, carnivores, human

126
Q

Pig placenta

A

Chorioallantoic, diffuse, epitheliochorial, central, folded, non-deciduate

Maternal and fetal epithelia closely apposed over most of the placenta.

Chorioallantois also forms areolae- regions of histotrophic placentation (non direct blood-to-blood.

127
Q

Carnivore placenta

A

Choriovitelline then chorioallantoic, zonary, endotheliochorial, eccentric, lamellar/ labyrinthine, deciduate, cross-current.

Marginal haematoma- green border- haemophagous zone.

Vestigial yolk sac.

128
Q

Horse placenta

A

Choriovitelline then chorioallantoic, diffuse, epitheliochorial, central, villous, non-deciduate, counter-current.

Spherical conceptus.

Chorioallantois = red membrane

Allantoamnion = white membrane

After birth check that the red membrane only has one hole.

Sites of endometrial cups- portions of chorionic girdle (fetal tissue) which invade and secrete eCG.

Although diffuse, there are microcotyledons.

129
Q

Ruminant placenta

A

Chorioallantoic, cotyledonary,(syn)epitheliochorial, central, villous, non-deciduate, cross-current

Fetal cotyledon + maternal caruncle = placentome

Bovine caruncle is convex, ovine caruncle is concave.

130
Q

What is a freemartin?

A

Some but not all mixed sex fraternal twins of cattle:

  • Vascular anastomoses between placentas
  • Masculinisation of heifer calves by androgens
  • Infertile- vagina may be very short
  • Also can exhibit bone marrow chimerism
131
Q

Mammary development

A

Develop along the milk line

Teats or nipples form as ingrowths of surface ectoderm which then canalise.

These ramify to form a discrete system of branching ducts.

132
Q

Ducts per teat in different species

A 
Ruminants 1
Horse, pig 2
Cats 6?
Dogs 12?
Humans >15
133
Q

Location of teats

A

Tethytheria (elephants, sea cows etc.): Axillary

Primates: Pectoral

Ruminants and horses: Inguinal

Pigs: Pectoral, abdominal and inguinal

Dogs, cats, rabbits: Axillary, pectoral, abdominal, inguinal

134
Q

Which animal has the most teats?

A

Multimammate rat (36)

135
Q

Anatomy of a cow udder

A

A consolidation of more than one mammary gland- 4 ‘quarters’ in cattle.

136
Q

Anatomy of cow udder- suspension

A

Lateral laminae:

  • collagenous
  • suspended from fibrous sheet attached to ventral pelvis and prepubic tendon

Medial laminae:

  • elastic extension of tunic flava
  • lengthens as udder fills–> teats point laterally
  • separated by loose connective tissue- used surgically
137
Q

Anatomy cow udder- cisterns and ducts

A

Most gland appears homogenous but there are ducts and sinuses that aren’t.

Varicose ducts lead to gland sinus (2100ml) leads to teat sinus.

Lactiferous sinus = milk sinus = GS + TS

138
Q

Anatomy of the teat sinus

A

Submucosal venous plexus- semi-erectile.

Mucosa- often ridged

Connective tissue with venous plexi, smooth muscle.

Papillary duct (streak canal) and orifice with smooth m. sphincter.

139
Q

Anatomy cow udder- arteries

A

External pudendal a. via inguinal canal.

Ventral perineal a.

140
Q

Anatomy cow udder- veins

A

External pudendal v. via inguinal canal

Caudal superficial epigastric vv. valves fail during lactation. It anastomoses with cranial superficial epigastric to form the milk vein.

Ventral perineal v.

141
Q

Anatomy cow udder- lymphatics

A

Superficial visible draining caudodorsally.

–> 2 superficial inguinal nodes (supramammary)

–> deep inguinal nodes via inguinal canal

142
Q

Anatomy cow udder- nerves

A

Three sources:

  • L1 and L2 to cranial surface
  • Genitofemoral L3/4 via inguinal canal to much of ventral surface
  • Pudendal n. S2-4 via perineum to caudal surface

Can be blocked for surgery; also sensory arm of milk ejection (‘let down’) reflex

143
Q

Mammary anatomy- sheep and goat

A
  • Two quarters
  • More pronounced median groove in goats
  • No papillary duct sphincter in sheep
144
Q

Mammary anatomy- horses

A
  • Two quarters- surprisingly small
  • Elastic and collagenous laminae as ruminants- prominent median groove
  • Thin, dark, almost hairless
  • ‘Wax up’ soon before parturition- a deposit of sebum and colostrum
145
Q

Mammary anatomy- pigs

A
  • 7 pairs of glands not really joined, but occasionally called an ‘udder’
  • more cranial glands appear smaller but may secrete more milk (bitch similar)
  • neonates have marginal tongue papillae, which may improve the seal on the teat (puppies similar)
146
Q

Mammary anatomy- dogs

A

10 glands supplied by:

- caudal superficial epigastric

147
Q

Mammary anatomy- rabbits

A

Usually 8 glands, occasionally 10

148
Q

Mammary anatomy- males

A

Present in many but not all species:

  • abdominal in carnivores and boars
  • scrotal in ruminants
  • preputial in stallions (uncommon)
  • not present in buck rabbits or male rats
149
Q

Mammary immunology

A
  • First milk secreted is colostrum
  • High content of immunoglobulins (IgG monomer > IgA dimer > IgM pentamer)
  • Secreted by a huge infiltration of lymphocytes which reach the mammary gland via blood from the peyers patches (?)
  • This is ‘maternal acquired passive’ immunity
  • IgA lines gut epithelium, others areabsorbed by specific FcR- mediated endocytosis in the SI
150
Q

How does colostrum differ from normal milk

A
  • Looks yellow
  • Higher protein
  • Lower fat
  • Higher Na+
  • Higher Cl-
  • Higher FS vits
  • Lower WS vits

Colostrum itself induces ‘closure’- the inhibition of its own uptake mechanism.

Later milk still contains Ig, but relatively more IgA

151
Q

How do female animals survive reproduction?

A

Breeding and growing up are the most risky energetically demanding things mammals can do.

Hormones are the means by which female mammals attune their reproductive activity to the environment.

152
Q

What reproductive decisions do females make?

A
  • When to start breeding- puberty
  • Which males to breed with- sexual selection
  • When to breed- seasonality, cyclicity
  • How many offspring- litter size, frequency
    (- When and whether to cease breeding- senescence)
153
Q

Cows- follicle selection

A
  • Ovarian follicles are continually recruited from the stock of primordial follicles
  • Stimulated to grow and develop by pituitary FSH, feedback on with E and inhibin
  • Follicular waves
  • Eventually larger follicles develop LH receptors
  • The number of follicles reaching this stage determines: ovulation rate, litter size, maternal drain, maternal and infant life and death
154
Q

Positive feedback by follicles

A

The follicles grow and eventually plasma [E] reaches a threshold. This feeds back positively on LH pulse frequency (hypothalamus) and amplitude (pituitary).

LH pulses start to overlap and summate –> runaway LH surge –> oocyte maturation, ovulation and luteinisation. An accompanying surge of E affects the brain to cause oestrus.

155
Q

What is ovulation?

A

A structural change in the follicle

156
Q

What is luteinisation?

A

Biochemical change in the follicle. Follicular cells hypertrophy, infill the follicle, and secrete P

157
Q

Ovulation and luteinisation in relation to each other

A

They occur in parallel- some P is produced before ovulation. Yet they can occur independently- e.g. in ovarian cysts

158
Q

What is the corpus luteum?

A

A solid temporary endocrine organ secreting P for most of the cycle- the luteal phase

159
Q

Luteolysis in cows

A

Cows are polyoestrus, so once the putative conceptus has had time to announce its presence, the CL must be destroyed. Destroyed by pulses of endometrial PGF2alpha- in a positive feedback interaction with luteal oxytocin pulses.

160
Q

How does PGF2alpha reach the corpus luteum?

A

Cannot reach the CL via the systemic circulation, as it is destroyed in the lungs. It reaches the CL via direct counter-current exchange: ovarian vein (blood from uterus) –> ovarian artery (blood to ovary)

161
Q

Recognition of pregnancy in cows

A
  • Pre-implantation anti-luteolysin
  • Interferon-tau: acts locally across a tiny distance to supress endometrial OTR expression. So it breaks the the PG
  • A few genes closely related to alpha- and beta- interferons OT feedback loop and prevents luteolysis.
162
Q

Cycle of the ewe

A

Show more seasonality than domestic cattle. Typical temperate ‘short day breeders’. Cycle mechanisms similar to cattle.

163
Q

Seasonality influences

A
  • Photoperiod
  • Weather
  • Nutrition
  • Horizontal/ vertical migration
  • ?lunar cycle
164
Q

Seasonality: melatonin

A
  • Some non-mammalian species also have a pineal eye for direct detection of light levels
  • At night pineal secretes melatonin, and indoleamine
  • Melatonin used artificially in sheep to alter breeding period e.g. regulin skin implant for both sexes in sheep
165
Q

Seasonality: effects

A

Autumn –> longer nights –> more melatonin

  • Acts directly and by inducing seasonal cycles of prolactin and thyroid hormones
  • Many targets- metabolic, appetite, pelage
  • Activates reproductive system by reproducing sensitivity of hypothalamic/pituitary to oestrogen negative feedback
166
Q

Senescence

A

Not seen in most mammals- cycle until death.

Cessation of cycling in women and killer whales (menopause):

  • remaining follicles unresponsive to gonadotrophins
  • i.e. not related to hypothalamus/ pituitary sensitivity
167
Q

Cycles of nanny goat

A
  • Derived from middle eastern goat (Bezoar)
  • Browser not grazer
  • Intermediate seasonality- short day breeder in temperate zones, climate induced in tropics
  • Very vocal in oestrus, discharge too
  • CL essential for P secretion throughout pregnancy
  • Very prone to pseudopregnancy- maybe because they’re induced ovulators
168
Q

Cycles of sows

A
  • Derived from wild boar
  • Limited evidence of remaining seasonality
  • Very high ovulation rate/ litter size, embryonic death is an important factor in litter size
  • Oestrus is evident- restless, prick ears, frequent urination, vulval swelling, stand to pressure
  • PRL is an important luteotrophin unlike other ungulates
  • PGF2alpha is the main luteolysin
  • MRP factor unknown
169
Q

Retained seasonality of mare

A
  • Harsh natural environment
  • Long day breeder, peak fertility at midsummer
  • Opposite response to melatonin vs sheep
  • Conflicts with aging system of the jockey club, want foals to be born as close to Jan 1st as possible
170
Q

Control of ‘litter size’ in the mare

A
  • Twinning is rare
  • Very tight control of FSH E, inhibin feedback
  • Live twins often not viable
  • Even if one dies it often debilitates the other
171
Q

Oestrus behaviour of the mare

A
  • Usually requires presence of male-‘teaser’
  • Obvious ‘straddling, winking, and urinating’
  • Donkey very different
172
Q

Luteolysis and MRP in mares

A
  • PGF2alpha is luteolytic, but only variably so
  • PGF2alpha analogues cause adverse side effects in horses
  • MRP signal unknown
  • The conceptus ‘fixes’ after 16 days, full implantation at 35 days before that time it migrates repeatedly from horn to horn- releasing a factor?
173
Q

Pregnancy endocrinology in mares

A
  • Fragments of chorionic girdle invade under the endometrium at day 35 to form endometrial cups
  • These secrete eCG from day 35-100
    (similar to LH)
  • This is not MRP- too late to arrest the cycle
  • Induces and supports a crop of new ovulations- multiple ‘accessory CLs’
  • For much of pregnancy, the hormonal milieu is dominated by a complex mix of E, not P
174
Q

Seasonal mono-oestrus in bitches

A
  • One oestrus per season, no ‘cycles’, no MRP
  • Most not attuned to time of year
  • Since pregnancy < inter- oestrus interval, it does not perturb the pattern of intermittent ovulation
175
Q

Gametes in bitches

A
  • Ovulate a primary oocyte still arrested in meiotic prophase I, rather than metaphase II
  • Ovulations may be spread over 48 hours or more and..
  • Sperm survive for long periods in the tract
176
Q

Progesterone levels in bitches

A

Progesterone levels increase near-linearly before ovulation and are predictive of fertility

177
Q

Pseudopregnancy in bitches

A
  • Hormone profiles near identical whether pregnant or not
  • Nesting, inappetance, abdominal swelling, lactation
  • May allow cross-suckling of dominant females’ pups
  • Ethinyloestradiol + methyteststerone ‘sensoral’ suppress pituitary lactotrophs (prevent lactation)
  • Bromocriptine ‘parlodel’ is a D-agonist, does have some side effects
  • Cabergoline ‘gala stop’ is a D2 agonist
178
Q

Seasonality in queens

A
  • Some seasonality: Jan-Mar, Jul-Sept
  • ?Opportunistic, like desert marsupials
  • Can start to breed simply if water/ food/ temp improve
  • Lower energy demands than bitches and can produce small litters, unlike sows
179
Q

Induced ovulation in queens

A
  • Increases chances of fertilisation (solitary species)
  • Continual production of waves of follicles
  • Some in continuous heat, some show ‘cycles’
  • Dramatic oestrus behaviour may worry owners- lordosis, rolling, calling, tail deviation
  • Coitus –> GnRH release –> LH surge –> ovulation
180
Q

Cycles in Jills

A
  • Derived from european polecat
  • Non-breeding Jills must be spayed
  • Reflex ovulators so continual follicle production –> hyperoestrogenism –> marrow depression–>

> Anaemia
Clotting disorders
Immune suppression
Hair loss tail, then flanks

181
Q

Cycles in the doe (rabbit)

A
  • ALl breeds derived from european rabbit
  • Jan-Sept breeding in wild, all year in captivity
  • Induced ovulation but often receptive in 2 week ‘cycles’
  • ? very rare diapause
  • Pseudopregnancy if mounted by bucks or other does- nest, hide, fur pluck, aggression
  • Pregnancy is about 31 days, can become pregnant almost immediately after giving birth
182
Q

Gravid uterus- diagnosis

A

Palpation:

  • Transabdominal in midpregnant carnivores
  • Rectal in horses, cattle and pigs
  • ‘Membrane slip, middle uterine a. fremitus’

Ultrasound:
- Transabdominal, per rectum, vaginal, echocardiography in humans

Radiography is good and reassuring for counting fetuses during birth.

Hormonal: but beware of pseudopregnancy (dogs), prolonged cycles (P), troph tumours hCG

183
Q

Gravid uterus- mare

A
  • Foals initially lies with back to the greater curvature of the uterine horn (spine ventrally), with its head towards the cervix
  • Early uterine contractions ‘roll’ the foal so it is spine-to-spine with the mare
  • Ventral to guts
184
Q

Gravid uterus- cow

A
  • Usually on the R, in the intestinal recess, displacing intestines dorsally and rumen to the L
  • Less often, may extend along R or even L flank
  • Calf lies with its back in the greater curvature (spine dorsally) and slightly to the R, with head towards the cervix
  • Uterus ‘sinks’ ventral to gas-filled gut
185
Q

Gravid uterus- size

A
  • Increases volume by 100x in cattle
  • Uterus cells hypertrophy rather than proliferate- thins but becomes heavier
  • Broad ligament often becomes more muscular
  • Ovary is pulled cranioventrally
  • Dramatic compression of abdominal and then thoracic organs- cd. VC, lungs etc.
186
Q

Birth canal- bony

A

Pelvic inlet between ilium and pubis.

Diagonal conjugata between ilium and ischium.

Vertical diameter between sacrum and pubis- narrowest stretch domestic animals have to get through.

187
Q

Problems with the birth canal in cattle

A
  • Surprisingly narrow
  • Sciatic tuberosities protrude into canal
  • Symphysis lies more directly below the sacrum, rather than caudal to it
188
Q

Birth canal- muscular

A
  • Sacrosciatic ligament (ungulates) + mid gluteal (carnivores)
  • Coccygeus (sciatic spine –> T proc Cd2-5)
  • Internal obturator
  • Levator ani (medial ilium –> haemal arch Cd7)
  • Ext. anal sphincter
189
Q

Rima vulvae

A

Bounded by labia minora
Labia majora not prominent (may be present)
Bounded by dorsal and ventral commisures

190
Q

Muscles of the vulva and perineum

A
  • Constrictores vulvae et vestibuli

- Ischiocavernosus everts vulva, esp. mare ‘winking’

191
Q

Clitoris

A
  • Lies dorsal to mares rounded commissure
  • Penis homologue
  • Lies in clitoral fossa (~prepuce), with dorsal frenulum
  • Very obvious in horses- site of CEMO?
192
Q

Perineum

A
  • Important in mares, due to the clinical effects of poor conformation
  • It is caudal body wall of the pelvic cavity
  • Complex of fibrous and muscular tissue around anus and vulva
193
Q

Vulva- ideal conformation

A
  • Labia firm and meet evenly to form a seal
  • 2/3 of rima vulvae lie below level of sciatic arch
  • Angle between commissures no more than 10 degrees from vertical
194
Q

What can poor conformation of the vulva lead to?

A

Air retention, urine pooling, faecal soiling

Reduced sperm viability in vagina, endometriosis, placentitis, fetal neonatal sepsis

195
Q

Changes to the birth canal at birth

A
  • Prior to birth relaxin , along with E and P, softens the collagenous structures of the tract, pelvis and perineum
  • ‘Insinking’ over sacrosciatic ligament in cattle, vulval ‘swelling’
  • Loosening of sacroiliac joint and pelvic symphysis
  • During birth the tail is usually raised
196
Q

Which animal completely splits its pelvic symphysis at birth?

A

Guinea pigs

197
Q

Causes of dystocia (maternal and fetal)

A

Maternal: Expulsive forces, the canal

Fetal: Oversize, malpresentations

198
Q

Pelvic causes of dystocia

A
  • Immaturity
  • Old fractures
  • Breed (achondroplasia decreases vertical diameter)
  • Other space-occupying lesions
199
Q

Uterine causes of dystocia

A
  • Torsion
  • Ventral abdominal rupture (ungulates)
  • Ventral deviation (pig) and retroflexion (horse)
  • Inguinal hernia
200
Q

Cervical causes of dystocia

A
  • Maybe hormonal

- Scarring, congenital

201
Q

Bladder causes of dystocia

A
  • Distension
  • Eversion (ungulates)- inside out
  • Rupture through floor of vagina (ungulates)
202
Q

Vaginal/ vulval causes of dystocia

A
  • Immaturity (any) or hymen (pig)

- Vulval stenosis (CKCS, Jersey)

203
Q

Dystocia- malposition

A
  • ‘Wrong’ part of fetus facing maternal spine
  • More common in horses due to need for early parturition ‘roll’
  • ‘Normal’ for humans
204
Q

Dystocia- malrepresentation

A
  • ‘Wrong’ part of fetus enters canal

- Very common and relatively unimportant in polycotous species

205
Q

Dystocia- malposture

A

All limbs are flexed until parturition, when the fetus takes up the ‘driving position’:

  • Carpal flexion, elbow flexion, shoulder retraction
  • Hip flexion, hock flexion
  • Lateral deviation of head
206
Q

Why do neonates have little control over their heat loss?

A

High surface are to volume ratio (larger mammals have better chance of survival)

207
Q

What does a neonates ability to vary heat production depend on?

A

Endogenous reserves and milk intake

208
Q

Energetically inexpensive ways to defend body temperature from mild cold

A
  • Vasoconstriction
  • Piloerection
  • Changes in posture to decrease SA
209
Q

Non-shivering thermogenesis

A

Dependent on brown adipose tissue:

  • High metabolic rate
  • Rich nerve supply
  • Good blood supply
210
Q

Where is brown adipose tissue distributed?

A

Around the neck, scapula, and thoracic vertebrae and some internal organs

211
Q

Which neonate has no brown fat?

A

Piglet

212
Q

Evidence for BAT being the major site of sympathetically activated non-shivering thermogenesis

A
  • Temperature within brown fat is greater than temp elsewhere
  • Hypoxia and the resultant decrease in blood-oxygen levels supresses heat production by BAT during cold exposure
  • In rabbits, excised brown fat from cervical and interscapular regions decreases metabolic response to the cold by 80%
213
Q

Mechanism for activation of BAT (theory)

A

Related to the uncoupling of substrate use and ATP production in mitochondria, and binding of catecholamines. Injecting adrenaline and noradrenaline has been shown to lead to an increase in heat production by brown fat.

214
Q

Role of type II deiodinase (D2) in BAT thermogenesis

A

Mediates the full thermogenic response of brown fat to adrenergic stimulation via increased thyroxine (T4) to triiodothyronine (T3) conversion.

215
Q

Maturational effects of glucocorticoids

A
  • Adrenal glands develop capacity to synthesise and secrete adrenaline
  • Change the set points of functioning endocrine glands
  • Maturational changes of organs
216
Q

Altricial offspring (e.g. rodents)

A

Rely on pups huddling together in their nest to maintain body temperature.

BAT matures post-natally.

Slow post-natal increase in UCPI correlates with the slowly rising ability to demonstrate non-shivering thermogenesis.

217
Q

Precocial offspring (sheep, cattle)

A

Able to rapidly switch on non-shivering thermogenesis following cold exposure to the extra-uterine environment.

UCPI is mainly increased immediately prior to birth.

Good defence of body temperature and immediately respond to noradrenaline.

Failure to switch on BAT, e.g. following pre-term birth, impairs heat production and results in hypothermia.

218
Q

Precocial offspring (piglets)

A

Lacks BAT, as its UCPI gene is non-functional

Entirely dependent on shivering thermogenesis following birth.

A large % of low birth weight piglets die perinatally, compared to piglets of mean or high birthweight.

Muscle glycogen is used primarily for thermogenesis and physical activity, and decreases more significantly than liver glycogen when exposed to cold temperatures.

219
Q

What is the prepartum cortisol surge caused by in most species?

A

Increased adrenal cortisol output

220
Q

What is the prepartum cortisol surge caused by in the rat and the horse?

A

Its effects are enhanced by a fall in the level of plasma corticosteroid binding globulin.

221
Q

Impact of stressful intra-uterine conditions on fetal cortisol levels

A

They become elevated due to HPA axis being activated earlier.

222
Q

What does thyroid hormone activate?

A

The brown fat around the time of birth.

223
Q

Endocrine and neural regulation

A
  1. Neural:
    - Innervation of adrenal medulla
    - Cortisol –> increases activity of PNMT –> converts NA to Adr
    - Motot maturation
  2. Endocrine:
    - pituitary-adrenal
    - pituitary-thyroid thermoregulation
    - insulin/ glucagon
224
Q

Insulin and glucagon around birth

A

Released in utero, with a large increase at birth.

After birth plasma [glucose] falls as no maternal input.

225
Q

Hypothalamic-pituitary-adrenal axis

A

Adrenal cortex:

–> Lungs: surfactant production, beta adrenergic receptors

–> Liver: glycogen, gluconeogenic enzymes, IGF gene expression, beta adrenergic and GH receptors

–> Gut: acid secretion, digestive enzymes, mucosal growth

–> Kidney: glomerular filtration rate, tubular Na reabsorption

226
Q

Excretion in newborns

A

Newborns pass sticky, black fecal matter called meconium (digested amniotic fluid, gastrointestinal secretions and bile)

227
Q

Kidney of newborn

A

Produced little urea as the animal is synthesising protein.

The collecting ducts of the newborn kidney are sensitive to the actions of antidiuretic hormone.

228
Q

Interuterine growth retardation (IUGR)

A

Impaired growth and development of the mammalian embryo/ fetus or its organs during pregnancy.

VRB (2 decks)

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