Week 1 Flashcards
What is viviparous?
Live young
What are the key aspects of reproduction?
* Production (an exocrine activity) and transport of ova
* Provision for deposition (copulatory organ) and transport of spermatozoa
* Provision of an environment for fertilization that nourishes and protects the conceptus
* Transport of conceptus and expulsion at parturition
* Endocrine activity (e.g. oestrogen and progesterone) which facilitates above activities
What is an ovum?
The female reproductive cell or gamete of animals, which is capable of developing, usually only after fertilization into a new individual
What are the four components of the reproductive system? Do they have the same embryonic origin?
- Germ cells
- Gonads
- Internal reproductive ducts
- External genitals
** each with separate embryonic origins
What are the germ cells?
Arise outside the gonads and migrate into them; these are the progenitors of sperm and eggs
What are gonads?
Testis and ovaries, arise on the medial surface of mesonephros (functions between the 6th and 10th weeks of embryological life– similar to the kidney– do not form the mature kidney); they promote germ cell proliferation and maturation and produce hormones/ growth factors that control development of other parts of the reproductive system
What are the internal reproductive ducts?
Transport germ cells and in females support fetal development, have different origins in males and females
What are the external genitals?
Incorporate parts of the urogenital sinus (endoderm- present in the development of the urinary and reproductive organs, it is the ventral part of the cloaca, formed after the cloaca separates from the anal canal during the fourth to seventh weeks of development), the proctodeum (ectodermal part of the alimentary canal– forms the lower part of the anal canal), and surrounding folds and the genital tubercle (develops into the glans penis or glans clitoridis)
What does it mean to say the reproductive system is dimorphic? How does this occur (2 ways)?
Showing features that are substantially different in males and females.
Occurs by:
- forms a common progenitor then direct its differentiation towards male or female
- form separate male and female tissues, then only promote differentiation the appropriate set
What are are primordial germ cells (PGCs)?
Progenitors of sperm and eggs. In all vertebrates they originate outside of gonadal tissues and secondarily move into the embryonic gonads.
** After the differentiation of testes or ovaries is underway, the germ cells (aka gonocytes) begin to proliferate rapidly. In human females, several million oogonia are generated before birth, but less than 2% survive until puberty, when hormonal stimulation initiates maturation of one or more latent oocytes during each estrus (menstrual) cycle
What are teratomas?
Some PGCs do not reach the gonadal ridges, most of these die, but a few may survive in ectopic locations and can later form tumors called teratomas. Teratomas contain irregularly arranged masses of many tissues including hair, teeth, cartilage, and bone, cardiac and skeletal muscle, thyroid, pancreas, gut, and kidney. These represent derivatives of all embryonic germ layers.
** usually benign, cystic tumors, although cells within the teratoma may become malignant. Most teratomas arise in or near the gonads, but occasionally are found at the base of the spinal cord, in the neck, mediastinum (mesenteries of heart and lungs), lungs, pericardium, and brain.
What is the path of differentiation of gonads into testes??
* Sex specific differentiation within the indifferent gonad is initiated earlier in males than in females
** First morphological changes are thickening of the basement membrane beneath the coelomic epithelium (tunica albuginea) and invasion of endothelial cells from the mesonephros
** Distal parts of many mesonephric tubules fuse with invaginated coelomic epithelial cords to form GONADAL CORDS, which become infiltrated by PGCs
** Later these cords cavitate to form SEMINIFEROUS TUBULES, where SPERMATOGENESIS will take place
**The mesonephric tubules remain and form the efferent ducts and rete testes which transport sperm to the epididymis (duct behind the testis, which sperm passes to the vas deferens), which is the region of the mesonephric duct that remains closely associated with the testis
** After testicular differentiation is underway, the caudal part of the mesonephros begins to degenerate, similar to the fate that already befell the cranial part of this organ
**
What are the Sertoli cells?
The first testis-unique cells to differentiate, derived from coelomic epithelium. These are critical for spermatogenesis following sexual maturation. In the embryo, these cells secrete AMH (anti-Mullerian hormone). This is a peptide hormone that initiates degeneration of progenitors of female reproductive ducts.
What is anti-Mullerian hormone (AMH)?
This is a peptide hormone that initiates degeneration of progenitors of female reproductive ducts.
What are Interstitial (Leydig) cells?
Some of the mesenchymal cells that surround the gonadal cords in the testis differentiate as interstitial (Leydig) cells. These cells synthesize and release testosterone, which is necessary to promote the subsequent differentiation and growth of mesonephric tubules and ducts. Testerosterone also promotes masculinization of the external genitals.
What does testosterone do during development?
promote the subsequent differentiation and growth of mesonephric tubules and ducts. Testerosterone also promotes masculinization of the external genitals.
What is the SRY gene?
Transcriptional regulatory gene that contains a region that codes for a DNA binding region of the peptide called HMG (high mobility group) – SRY binds to DNA and induces a conformational change, in effect creating a bend in the DNA. ** SRY marks the first gender specific event in gonadogenesis– activates Sox9 (autosomal gene)– expressed on both male and female gonadal ridges– sox9, the testis determining factor, binds to an AMH promoter, therefore leading to the regression of the paramesonephric (muellerian) ducts
** the SRY gene makes males– or without it, = female
One gene located on the Y chromosome (from a male) is required for male development. The gene activates other “boy” genes– without it, other “girl” genes are activated.
What are the paramesonephric (muellerian) ducts?
Paired ducts of the embryo that run down the lateral sides of the urogenital ridge and terminate on the sinus tubercle in the urogenital sinus. IN the female, they will develop into the uterine tubes, uterus, and cervix and the upper one third of the vagina. IN the male, they are lost. Mesodermal origin.
What are ovarian follicles? When can they become clinically relevant?
In females, the invaginating cords of coelomic epithelium (serosa) break apart into vesicular spheres called ovarian follivles, each of which initially contain multiple germ cells. Most of these are located around the margin of the indifferent gonad. All of the mesonephric tubules degenerate, as a result, the follicles fill the entire ovary. The mesonephric ducts largely degenerate in females, though nonfunctional remnants are occasionally found near the ovary and the urogenital sinus. These can be of clinical consequence if they become cystic.
What is Wnt4?
Signaling factors critical to cell determination and differentiation in many systems, it was the first signaling molecule after AMH to be identified in early gonadogensis. Wnt4 has a suppressive effect on the differentiation of stroid producing cells, including interstitial (Leydig) cells, and Wnt4 mutations that specifically block this function result in females with excess steroid hormone production in their gonads, including low levels of testosterone.
** overexpression of Wnt4 produces a range of abnormalities in XY individuals. these range from mild e.g. cryptorchidism, to full feminization of teh reproductive ducts and external genitals.
What is cryptorchidism?
The absence of one or both testes from the scrotum.
What gender are the mesonephric ducts retained and what do they develop into?
* In males, mesonephric ducts are retained. Within the mesonephros, where efferent ducts derived from mesonephric tubules are present, the duct becomes the epididymis. Caudally the mesonephric duct differentiates into the deferent duct (ductus deferens), which carries sperm from the epididymus to the urethra
* Near its junction with the urogenital sinus, a diverticulum from each mesonephric duct forms the seminal vesicle.
What is the ductus deferens (deferent duct)?
which carries sperm from the epididymus to the urethra
Where do the prostate gland and the bulbourethral glands arise from?
Arise as multiple small diverticula from the roof of the urogenital sinus immediately caudal to the mesonephric duct. This region becomes part of the pelvic urethra. All male mammals have a prostate gland, but some can be reduced or absent e.g. cat, dog.
Where do the female reproductive ducts differentiate from?
NOT associated with the mesonephric system. The “plumbing” components of the female reproductive system develop in both male and female embryos.
* A longitudinal band of thickened serosa forms along the ventro-lateral margin of each mesonephros. Cells in each band invaginate, forming a pair of long goorves that close to form the paramesonephric ducts–> the thickening, invagination, and closure extend caudally along the dorsolateral margin of the coelum–> as the ducts elongate caudally– they merge to fuse with the urogenital sinus
What prevents oocytes to be released from the surface of the ovary from escaping into other parts of the peritoneal cavity?
The arrangement of serosal folds functionally prevents oocytes released from the surface of the ovary from escaping into other parts of the peritoneal cavity, and directs them into the lumen of the duct.
What is different about the paramesonephric ducts between humans and other mammals?
* in humans the paramesonephric ducts differentiate as the uterine tubes (formerly called oviducts)– and the region where they are joined is the uterus, which is the site of the placental contacts during pregnancy.
* in most mammals, embryonic development is supported along a much greater length of paramesonephric ducts; these are referred to as uterine horns. the uterine tubes remain as short segments close to the ovary and are the sites where fertilization occurs. The body of the uterus is often relatively small.
What forms the vagina in development?
The roof of the urogenital sinus evaginates at the site where the paramesonephric ducts enter. This evagination together with the distal part of the paramesonephric ducts forms the vagina, which is of both endodermal (urogenital sinus) and mesodermal (paramesonephric ducts) origin.
What is the vestibule?
In non-primate mammals, the vestibule is the chamber located between the sites of urethral and vaginal entrance and the body wall. It is largely of urogenital sinus origin, but its caudal region includes contributions from the surface ectoderm.
What is the genital tubercle?
Mesoderm ventrally adjacent to the UGS proliferates to form a swelling, the genital tubercle. This is present in both male and female embryos. After the onset of sex- specific gonadal secretions, both the growth and location of the genital tubercle change in male embryos. It will eventually go on to form the external genitals
What do the cloacal folds become?
Extending dorsally from the base of the genital tubercle on either side of the cloacal plate are cloacal folds (genital folds). These ridges extend laterally as genital swellings (labioscrotal swellings). After separation of the rectum from the urogenital sinus, the cloacal folds become anal and urethral folds.
What do urethral folds become?
In females, urethral folds and genital swellings enlarge to form the labia. Ventrally they partially circumscribe the genital tubercle, which will form the clitoris.
** In males, the urethral folds meet in the midline and fuse, initiating the closure of the penile urethra. This apparent increase in the distance from the anus to the base of the penis (anogenital distance) is the earliest external sign of male development. The genital swellings remain as the scrotum.
What converts testosterone to DHT? What is DHT?
The enzyme 5-alpha-reductase type I converts testosertone to dihydrotestosterone (DHT) which is the essential activator for growth and differentiation of precursors of the penis and scrotum.
What happens when there is a dysfunction of 5-alpha-reductase-1?
Renders the external genitals nonresponsive to testosterone, a condition referred to as testicular feminization. Complete loss of this reductase in XY fetuses produces an infant tha tmay appear female at birth, but will later not menstruate and at puberty will develop male secondary sex features.
What is a male’s phenotype? Female?
XY, female= XX
What is an example of a common progenitor being directed to differentiate along either of two pathways?
Gonad
What is the 47XXY genotype (Klinefelter syndrome)?
** Intersex condition
A result of meiotic X-chromosome nondisjunction during oogenesis. These persons are phenotypically male. They have male internal reproductive tracts (i.e. mesonephric ducts), lack oviducts, and uterus, and have male external genitals. Small testes (primary hypogonadism) and lack mature sperm. Due to reduced levels of post-puberty circulating testosterone, they develop secondary signs such as increased fat accumulaton on the hips and unusually long extremities.
** Many calico (tortoiseshell) cats affected and 3 color males (orange and not orange- need two X chromosomes)
What is the XO genotype in females (aka Turner syndrome)?
Occurs less frequently than XXY individuals.
** intersex condition
* Affected persons are phenotypically female, sterile, and usually present with short stature, lateral webbing of the neck and cardiac malformations.
** Horses– female but may be small for age and breed. Ovaries are small and inactive and the individual is sterile
What is “intersex conditions” (pseudohermaphroditism)?
Secondary sex characteristics of an individual do not match the gonads (ovary or testis).
* external reproductive organs may look like typical penis or clitoris or in some cases may look “intermediate”
What is a true hermaphrodite?
* Both ovarian and testicular tissue is present
What is a Freemartin?
* More than 90% of heifers who are born as twin to a bull calf, are sterile. These animals become XX/XY chimeras due to placental anastamoses, in which blood (cells) cross from one twin to the other. The external genitals often show some masculinization, such as enlarged clitoris or increased ano-genital distance. Typically, the internal reproductive ducts are ambiguous.
** picture: the one on the right is normal– the abnormal- vagina is short- without ultrasound, you can just measure
What do the uterine tubes do? (fallopian or oviduct)
Funnel shaped entrance (infundibulum)– located at the ovarian end, leading into the uterus at the other. The uterine tubes collect and conduct the ova to the uterus and are generally the site of ferilization of the oocyte.
What is the uterus?
A single structure but comprising 2 horns (which are the most developed region in the domestic animals), a body (relatively short, single tube), and a cervix (thick walled caudal portion of the uterus akin to a valve– closed except during oestrus or parturition. The uterus receives the zygote and provides an environment for implantation and development of the conceptus.
What is the vagina and vestibule?
The contiguous distal portions of the tubular genitalia serving as the copulatory organ and birth canal. The junction between the vagina/ vestibule is marked by the external urethral orifice.
What is the vulva?
The external opening of the tract and comprises a median cleft that is flanked by a labium either side, which meet dorsally and ventrally at the dorsal and ventral commissures.
What are the major areas of variation seen among the domestic animals?
* ovarian size, shape, internal organization and location, uterine shape, relative sizes of the uterine horns and uterine body, internal morphology and location, cervical length and the tortuosity of the cervical canal.
* Birds– usually a single ovary (usually left) that appears lik ea bunch of grapes-surface covered with very large oocytes
What is the oestrus cycle?
Comprises alternating periods of receptivity for mating and periods of indifference. The lengths of thse periods are their frequency are species dependant
What is oestrus?
The period of receptivity and generally coincides with ovulation (release of the oocyte). Around oestrus the follicles in the ovary grow to maturity and rupture, the cervix opens and the vagina/ bulva prepares for copulation. The trace prepares for transport of spermatozoa and fertilization of the ova.
What the corpora lutea?
** following oestrus the corpora lutea form from the ruptured follicles and the uterine vasculature increases and the uterine mucosa prepares to support the conceptus. If fertilization fails the corpora lutea degenerate and a new set of follicles begin to mature and the uterus begins to return towards its resting state
** if fertilization is successful the corpus lutea in the ovary are retained and the uterine changes (mucosal and vascular) are more marked with the formation of the placenta to nourish the conceptus during gestation
Location of ovaries in ruminants and pigs vs. other species
Ruminants and pigs– ovaries are located close to or at the pelvic inlet having undergone a caudal migration somewhat akin to “descent” as applied to the male gonads which descend into the scrotum.
** coil shaped in ruminants and convoluted in the sow
** other species- sublumbar region caudal to the kidneys- near where they arise embryologically
What is unique about the equine ovary?
The cortical tissue (stroma, follicles, and corpora lutea) are located in the centre of the organ, while the medullary tissue occupies the outer region. The cortical tissue comes to the surface at the depths of a small depression (ovulation fossa) on one side of the ovary.
What is the mesovarium?
medulla consists of loose connective tissue containing vessels and nerves and contacts the surface at the hilus- Where vessels and nerves enter and where the ovary attaches to its mesentery (mesovarium)
** ovarian a. runs in the mesovarium
What is the cortex of the ovary made up of?
Dense stromal tissue of plump fibroblast-like cells and connective tissue. Scattered within the cortex are spherical structures- follicles and corpora lutea.
What are ovarian follicles? What are corpora lutea?
Fluid filled spheres which contain oocytes, and are in various stages of development. The corpora lutea are also spherical bodies but consist of endocrine cells which produce progesterone to support pregnancy.
** Follicles and corpora lutea go through cyclic changes of development, rupture and regression. Thus the composition and appearance of the cortex varies associated with the stage of the oestrus cycle in the mature animal. It will contain follicles (each containing an ovum) at various stages of developemtn and varying in size from microscopic primordial follicles to macroscopic mature tertiary follicles…
What is the major factor influencing siz of the follicles?
The amount of follicular fluid present.
What is atresia?
Follicles undergoing degeneration
What develops from follicles following ovulation?
Corpora lutea– generally attain a similar size to that of the mature follicle of a given species.
** they undergo degeneration (if no pregnancy or after parturition) to form scars called corpora albicantes– which gradually shrink over successive cycles and eventually disappear
What gives the ovaries the irregular, nodular appearance?
Follicles and corpora lutea generally protrude from the ovarian surface– the degree depends on species
What do follicles produce? What do corpora lutea produce?
Oestrogen and cause signs of oestrus or heat and promote conditions favouring fertilization and support of the ovum and zygote.
* Corpora lutea produce progesterone which supports pregnancy
What is the tunica albuginea?
Surrounding the cortex is a thin layer of dense connective tissue- tunica albuginea. This underlies the ovarian surface epithelium which is a simple epithelium of variable height. This epithelium is continuous with the ovarian mesentery.
What does the infundibulum at the ovarian end of the uterine tube do?
Leads to the abdominal opening of the tube- the ostium- located at its base. The free margin of the infundibulum is irregular and forms processes called fimbriae which extend towards the ovary.
** the infundibulum and fimbriae become active and motile at ovulation and move close to the ovary to catch and sweep the ova towards and through the ostium into the uterine tube
What does the ostium lead to?
Relatively wide lumen of teh initial segment called the ampulla, this is followed by the isthmus which has a narrower lumen but equal length. The isthmus ends at the uterotubal junction with the uterine opening which may be located on a small papilla which projects into the uterine lumen or the transition may be gradual depending on species.
What does the uterus consist of?
Uterus, body, cervix
** largest portion of the reproductive tract and provides for the protection and nourishment of the embryo/foetus until parturition, and assists in the expulsion of the foetus at term
What is different about uterine horns in a pig vs. ruminant?
Luminal surface may possess varying order of folds in pigs
Or
rows of small mounds (caruncles) in ruminants
What is the cervix?
Thick walled terminal portion of the uterus and is located between the uterine body cranially and the vagina caudally.
Wall comprises smooth muscle and dense fibrous tissue which makes it easily distinguished by palpation in the large domestic animals. It acts as a sphincter or valve regulating access to the uterus from the vagina.
** a seal is completed with a plug of cervical mucous
What is the vagina?
Thin walled, highly distensible tube extending from the cervix to the vestibule. Usually in a collapsed state. Only a small cranial portion of the dorsal aspect is covered by peritoneum, the site offer surgical access to the abdominal cavity (via the rectogenital pouch).
** forms the cranial portion of the copulating organ of the female birth canal. It receives the penis of the male during copulation and is the site of seminal fluid deposition in ruminants.
What is the hymen?
* found near the caudal end of the vagina and marks the boundary between structures of different embryological orgins. It is poorly developed in the domestic animals ranging from a low annular fold to a series of short transverse folds or irregular tags.
What is the vaginal fornix?
The annular recess at the cranial end of the vagina– formed around the vaginal portion of the cervix.
What is the border between the vagina and vestibule called?
External urethral orifice
WHat is the vestibule?
The vestibule is
the short terminal portion of the tubular genitalia that is shared with the urinary
system.
It is the caudal part of the copulatory organ and birth canal and extends from the vagina to the
vulva. It lies caudal to the ischiatic arch and is generally incli
ned ventrally.
What anatomical features make catheterisation of the urethra in a female difficult?
* the external urethral orifice is raised above the tract floor on a small mound or HUMMOCK in the bitch (where the urethra enters), while the cow and sow there is a small pocket called the suburethral diverticulum.
WHat are the vestibular glands?
The wall of the vestibule has mucous glands– major and minor. Provide lubrication for the tract in preparation for copulation and parturition. Mucus production is most pronounced during oestrus.
* minor vestibular glands- several rows of simple galnds opening on the lateral +/- ventral wall of the vestibule in the dog, pig, and horse, and are variably present in sheep
What is the vestibular bulb?
* the wall of the vestibule contains extensive venous plexuses. IN the bitch and mare these form discrete patches on either side. This cavernous or erectile tissue is homologous to the penile bulb in the male.
What is the clitoris?
Comprises of 2 crura, a body and a glans and is homologous to the male penis. It contains erectile tissue in the mare and bitch.
** the glans in the mare has multiple sinuses which can serve as hideouts for venereal pathogens (clitoralfossalectomy to prevent- probably uncommon)
** Mare has more erectile tissue in the clitoris (winking)
** older mares it can start to slope dorsally and get faecal contamination
What is the constrictor vestibuli m.
Vestibule is encircled by circular skeletal muscle.
What is the vulva?
External opening of the female repro tract. Comprises of a vertical cleft flanked laterally by 2 labia. The labia meet dorsally at the dorsal commissure and ventrally at the ventral commissure. (the ventral commissure encloses the clitoris).
Describe the labia
** the skin of the labia is common integument with many sebaceous and sweat glands with fine hair
** the labia contain fat and muscle bundles, the latter being the constrictor vulvae m.
What ligament suspends the female repro tract from the roof of the abdomen? What 3 parts is it made up of?
Broad ligament
- mesovarium
- meosalpinx
- mesometrium
What is the mesovarium? What are the other two ligaments associated?
The most cranial part of the broad ligament and supports the ovary. It attaches to the hilus and carries vessels and nerves to the ovary.
** cranial free border is thickened to form the suspensory ligament of the ovary
** proper ligament- runs between the uterine pole of the ovary to the cranial tip of the ipsilateral uterine horn
What is the mesosalpinx?
* supports and encloses the uterine tube– a fold of peritoneum arising from the lateral surface of the mesovarium – which forms a small pouch, the ovarian bursa (which contains the ovary in carnivores, but is too small to do so in the mare)
What is the mesometrium?
* supends the uterine horns, body and cervix and is continuous with the perimetrium of the uterus (outer serosal covering). It carries the vessels and nerves serving the uterus.
** the lateral surface of the mesometrium on either side has an additional fold of peritoneum which runs to the inguinal canal. Each one’s cranial free border carries a round ligament of the uterus (a vestigial structure) which continues through the inguinal canal into the vaginal process. Varies in developement depending on species (may be seen in carnivores, hores and cow)
** uterine a. runs in the mesometrium
What is the arterial arcade? What arteries contribute?
The blood vessels supplying the reproductive tract form numerous anastomoses which form an arterial arcade running the length of the uterus. This arcade receives contributions from the following arteries: ovarian a., uterine a., and vaginal a.
Where does the ovarian a. arise from? What does it branch to?
Arises from the aorta–> runs within the mesovarium–> gives rise to an ovarian branch, a uterine branch and a branch to the uterine tube
Who has the uterine a.? Where does it run? What does it give rise to?
Uterine a. runs within the mesometrium and gives rise to branches that run cranially and caudally. The vessel arises from the internal iliac a. via the umbilical a. in the ruminant and pig and from the external iliac a. in the horse. It is absent in carnivores. When present, it is the major supply to the uterus.
What is fremitus?
In large ruminants and the pig, palpable turbulence can be felt in these vessels at certain stages of pregnancy (cow 80-90 days + in artery of the gravid horn)
Which is the most caudal of the main blood vessels supplying the repro tract? Where does it arise from in diff. species?
* vaginal a. is th emost caudal– gives rise to branches running cranially and caudally
* internal pudenal a in the horse
* internal iliac a. in the ruminants and pig
Wolffian duct- mesonephric system
Tubular genitalia- a system of connected muscular tubes
Infundibulum is a mitt of the uterine tube. Catches the ovum (baseball)
** ovum is fertilized in the uterine tube
What is this picture? What is unique about the horse’s ____ (#4)?
Ovary (with the hilus- nerves and blood vessels)
When the follicles (bumps) rupture- they form the corpus luteum.
** Horses are inside out
What is in the testis?
* Seminiferous tubules- myofibroblast cells– having to do with squeezing the sperm when it is mature into the epididymis– on the outside at the lumen of the seminiferous tubules are the germ cells (spermatogonia)– after maturity they tend to undergo mitosis and meiosis. In the lumen of the tubule– spermatazoa
* Sertoli cells - supportive cells for the sperm
What is in the seminiferous tubules?
What is interesting about the cells when creating spermatozoa?
They are joined until they are spermatocytes
How is sperm conducted to the urethra?
Testis–> epididymis–> ductus deferens (ampulla at the top– V shaped)– in some animals widens out to become ampulla… which often secretes chemicals that assist in seminal fluid… ampulla can sometimes be considered an accessory gland in SOME species: ruminants, horses, and dogs (remember by thinking they all PULL THINGS)
** the last part is the ejaculatory duct in horses and ruminants
What is seminal plasma (semen)? What produces semen?
Semen is the fluid that nourishes sperm.
Accessory glands produce semen (a few different ones)
What are seminal vesicles?
* adds parts to semen
What are bulbourethral glands? What are the other glands that have to do with semen?
Cylindrical structures in bulls- add parts to semen.
** prostrate gland also adds to the seminal plasma– colourless, slightly acid fluid, high concentration of proteolytic enzymes, zinc and copper (especially dog)
** seminal vesicles- mesonephric duct origin– slightly yellowish secretion, presence of flavines, potassium and fructose concentrations. Ergothionine (in the boar especially) citric acid, proteins, prostaglandins are also present
Barbs on the penis cause cats to ovulate
What is the colliculus seminalis?
Ridge of tissue– multiple ducts open in the region of the colliculus seminalis of the urethra mucosa
What are the background influences on male reproduction to be considered?
What are some of the areas of the brain and some of their functions needed by the male?
Optic chiasm, pituitary gland, hypothalamus, sella turcica (bone)
What evokes libido?
* Male sexual behaviour patterns imprinted on the brain in foetal/ neonatal life
* Testosterone in the adult evokes the imprinted pattern
* Testosterone threshold
* previous experience, training
*Management
* Sexual stimulation/ environment prior to mating
* Pain often adversely affects ability to serve
Flehmen- a sign of sexual arousal
What are some causes of fluctuation in fertility?
Function of the horse pineal gland
What is the hypothalamic-pituitary-gonadal axis?
What is the anterior pituitary’s role in reproduction?
Melatonin’s role in reproduction?
What axis produces melatonin? What is another chemical involved?
Sequence of events in the hormonal control of spermatogenesis in the bull
Spermatogenesis
What drives puberty? How old in bulls? Rams? Stallions? tomcats? dogs?
Which hormone triggers high surges of GnRH? WHat is the follow on effect?
Due to high levels of oestrodiol–>GnRH–> leads to LH/ FSH production
What is the average age (range) of puberty in different species? What plays a role intraspecies?
Breed
What makes a male and a female?
What is TDF?
Cervix- designed to close and keep out any pathogens
8? 10?
8- cervix
10- vagina
Cervix– tight and closed– probably pregnant in diestrus. (This is a endoscopic view of the external uterine orifice)
IF it is floppy and open– in oestrus
What is a synonym for the vestibule?
Greeting room
VX?
Vaginal fornix- annular recess around vaginal portion of cervix (blind pouch)
Free edge of the broad ligament is the round ligament
Blood supply to carnivore ovary and uterus
What are the two phases of the oestrus cycle?
* Follicular phase- dominated by a dominant follicle (or multiple with litter species) that produces oestradiol
* Luteal phase- by a corpus luteum (or corpora lutea in litter species) that produce progesterone
Talk through this diagram
Talk through this
Proestrus: as P4 drops, FSH and LH increase in response to GnRH. FSH and LH lead to production of oestradiol by ovarian follicles
Oestrus: dominant follicles produce oestradiol and inhibin. Inhibin suppresses FSH secretion and oestradiol leads to the stimulation of the surge centre in the hypothalamus: increase in GnRH, followed by an LH peak (FSH does not surge simultaneously beacuse of the negative feedback from inhibin).
What are the four processes of antral follicles?
Recruitment: a cohort of follicles are selected and start growing
Selection: A few undergo atresia and some are selected
Dominance: one (in monotocuous species) reaches dominance and starts producing inhibin
Atresia: the other undergo atresia because of lack of FSH (due to negative feedback from inhibin)
What occurs on account of the preovulatory LH surge?
*Ovulation requires destruction of follicular tissue due to hyperaemia–> oedema–> elevated hydrostatic pressure (angiogenic factors have been found in follicles suggesting they control their own bloodflow)
What happens during the luteal phase?
- corpora lutea formation
- production of progesterone
- luteolysis
*When the follicle ruptures and the fluid leaks out, blood vessels also rupture and fill the new cavity with blood–> CORPUS HAEMORRHAGICUM forms.
** theca interna and granulosa cells get through into folds and mix–> they undergo luteinization (transform into luteal tissue). CL is a mixture of larget luteal cells (LLC), former granulosa cells, and small luteal cells (SLC), former theca interna cells. They are both steroidogenic, hence producing progesterone.
What are the effects of progesterone?
Negative feedback on the GnRH neurons–> less LH and FSH produced
* positive effect on the endometrium (gland secretion increases, contractility decreases), cervix closes
Why is the uterus necessary for luteolysis in most species? SO what happens with loss of uterectomy?
Uterus produces prostaglandin F2alpha that enters the uterine drainage, it then diffuses from the uterine ovarian vein into the ovarian artery and is transported directly to the ovary where it causes luteolysis
Talk through this diagram
What are the 5 layers of the scrotum?
- Skin and tunica dartos- thin with sweat glands, hair, connective tissue, elastic fibres, and smooth muscle
- External spermatic fascia- fibrous connective tissue
- Cremasteric Cremastic fascia- cup shape aponeurotic attachment for the cermaster m. which arises from the internal abdominal oblique m.– which action is to alter the position of the testis relative to the body wall
- Internal spermatic fascia- thin layer that supports the parietal vaginal tunic
- Parietal vaginal tunic- serosal membrane lining each scrotal cavity and reflects scrotal contents at the mesorchium to become the visceral vaginal tunic
