urogenital anatomy prac

Question 1

what is the urethra

male

Answer 1

striaght tube opening to surface at ecternal urethral orifice and divisible into:
- pelvic urethra (homologue of the female vestibule)
- penile urethra (no counterpart to female)

Question 2

what is the penis

Answer 2

an extracloacal component developed to facilitate internal fertilisation. urethra extended beyond the pelvic outlet and enclosed within the components derived from the cloacal wall (corpus cavernosum, corpus spongiosum)

Question 3

what is the corpus cavernosum

Answer 3

paired masses of erectile tissue forming the bulk of the penis. diverge proximally in the penile root to attach to ischiatic arch. join to run forwards in the body of the penis and terminate within the glans of the penis

Question 4

what is the corpus spongiosum

Answer 4

a single mass of erectile tissue around the urethra. it expands 1) proxmally as the bulb of the penis between the diverging limbs of the corpus cavernosum penis ; 2) distally as the corpus spongiosum glandis around the corpus cavernosum in the glans penis at its free end

Question 5

list accessory structure of the male reproductive tract

Answer 5

• vesicular glands
• prostate gland
• bulbourethral gland

Question 6

what are the location of the vesicular glands

Answer 6

paired, lying dorsolateral to the neck of the bladder. often enlarged seminal vesicles which are then pouches opening into the deferent ducts just before these empty into the pelvic urethra

Question 7

what is the anatomical location of the prostate gland

Answer 7

unpaired, surrounding the pelvic urethra at the point of union of the urethra and deferent ducts.

Question 8

what is the anatomical location of the bulbourethral gland

Answer 8

paired lying dorsal to the caudal end of the pelvic urethra closely related to the bulb of the penis. Vestibular glands comparable to the bulbourethral glands of the male are present in the lateral walls of the female vestibule.

Question 9

what are the 3 major muscular components of the penis concerned with erection and ejactulation. state their anatomical location

Answer 9

• Ischiocavernosus – paired, around the divergent limbs of the CCP aiding the penile anchorage and in the preliminary stages of erection.
• Bulbospongiosus – continuation of the urethral muscle around the pelvic urethra. It covers the urethral bulb and much of the CSP aiding in ejaculation.
• Retractor penis – paired, in relation to its origin from sacral vertebrae and external anal sphincter. The two parts join and the single strand of muscle attaches to the urethral (ventral) surface of the root and body of the penis. Important during the subsidence of erection.

Question 10

what is the prepuce and what are its purposes

Answer 10

the sheath of skin from the belly wall which covers the free end of the penis. It serves in two main ways:
* As a protective covering for the sensitive skin over the surface of the glans penis during the flaccid condition of the penis.
* Provides a reserve fold of skin covering the body of the penis when it extends during erection.
* The internal surface of the prepuce may also contain preputial glands whose primary function is to provide lubrication during copulation.

Question 11

what is the inguinal canal, where are they located and what is their purpose

Answer 11

Inguinal canal – The inguinal canals are paired obliquely orientated passageways through the musculature of the abdominal wall. They are separate from the femoral rings which carry the femoral artery, vein and nerve. Present in both sexes on either side of the midventral line cranial to the pubic brim. They serve as passageways for the various vessels to/from the testes in all males with extra-abdominal testes, or for the vaginal processes in bitches only.

a. Deep Inguinal ring – The entry into the canal from the abdominal cavity bounded by transversalis fascia and abdominal muscles.
b. Inguinal canal – The canal itself bounded by the extension of the transversalis fascia and abdominal muscles. It is more of a flattened slit than a canal.
c. Superficial Inguinal ring – The exit from the canal into the subcutaneous tissues bounded by external abdominal fascia combining with the transversalis fascia of the canal and by aponeurosis of the external abdominal oblique muscle.

Question 12

what is the vaginal tunic (process in the bitch) what are its constituents

Answer 12

The vaginal processes are outpouchings of the parietal peritoneum of the abdominal cavity which pass through the inguinal canals. The processes contain the vaginal sacs which are continuous with the abdominal cavity. The peritoneal ring formed where the process passes into the inguinal canal is the vaginal ring which therefore marks the position of the deep inguinal ring. Within the inguinal canal the vaginal processes attach to the tranversalis fascia lining the canal. All females have a vaginal ring and inguinal canal to allow for the external pudendal vessels, but only the bitch has the vaginal process which projects into the inguinal canal.

In males the process ‘contains’ the testis, its ducts, blood vessels, lymphatics and nerves, which are unsheathed by visceral peritoneum. The process therefore consists of:

a. Parietal vaginal tunic – The serous membrane forming the wall of the vaginal process, continuous with the parietal peritoneum at the vaginal ring.
b. Visceral vaginal tunic – The serous membrane investing the testis and its appendages.
c. Mesorchium – The serous membrane connecting the parietal and visceral layers of the vaginal tunic and forming the mesentery of the testis and its appendages. In the fetus the mesorchium suspends the testis from the dorsal abdominal wall and contains the testicular vessels and nerves. After testicular decent into the vaginal process the testicular vessels and nerves are greatly lengthened where they enter the spermatic cord but are still housed in the mesorchium suspended from the caudo-dorsal wall of the vaginal process.
d. Vaginal sac – The potential cavity within the vaginal process between parietal and visceral vaginal tunics, continuous with the peritoneal cavity at the vaginal ring and containing sufficient fluid to allow friction free movement of the two layers.

The vaginal processes lie in subcutaneous positions enclosed in a layer of spermatic fascia continuous at the superficial inguinal ring with the transversalis fascia and the external abdominal fascia. The skin covering the terminations of the vaginal processes, in which the testes are situated, is modified to form the scrotum. The testis is anchored at the base of the vaginal process by the ligament of the tail of the epididymis attaching to the spermatic fascia.

Question 13

what is the spermatic cord

Answer 13

the aggregate of strucures carried through the inguinal canal by testicular descent. it is in 2 parts:
- testicular blood vessels and nerves in the mesorchium
- deferent duct and its blood vessels in the mesoductus deferens

Question 14

which muscles make up the muscles of the vaginal process

Answer 14

1. Cremaster – sandwiched between the layers of spermatic fascia, from the abdominal wall muscle to fascia at scrotal base.
2. Dartos - smooth muscle beneath scrotal skin attaching to the spermatic fascia.

Question 15

outline some comparative anatomy points in the stallion

Answer 15

• Musculocavernous type of penis that greatly increases in length and diameter during erection.
• Glans penis is complex – corona becomes greatly enlarged during erection. During ejaculation corona flattens out in the shape of a basin.
• The urethra sits inside the urethral fossa (relevance: CEM swabbing).

Question 16

outline some comparative anatomy points in the dog

Answer 16

• a. Musculocavernous type of penis that undergoes a great increase in diameter after intromission.
• b. The glans includes the bulbus glandis and pars longa glandis erectile bodies; both of which are extensions of the corpus spongiosum penis.
• c. The os penis is located in the distal part of the body of the penis and the proximal part of the glans.
• d. The corpus cavernosum penis, which anchors the penis to the pelvis, engorges and becomes stiff during precopulatory sexual excitement. Since the corpus cavernosum penis is attached to the os penis distally, the penis is a rigid structure from the pelvis to the tip of the os penis during copulatory thrusting.
• e. Engorgement of the corpus spongiosum penis occurs after intromission, and because the bulbus glandis when engaged is too large to be pulled out of the vagina, dogs remain locked during copulation until the erection of the bulbus glandis subsides.

Question 17

outline some comparative anatomy points in the tomcat

Answer 17

• a. Os penis is present.
• b. Glans penis has papillae (cornified) on dorsal and lateral sides of the glans penis (these regress after castration).
• c. During urination the penis is directed caudodorsally if spraying or caudoventrally if squatting like the female during urination.
• d. During copulation, penis is directed ventrocranially.
• e. When relaxed, the urethra is sigmoid (relevance: urinary catheterization).

Question 18

outline some comparative anatomy points in the bull/ram

Answer 18

• a. Fibroelastic type penis. Little increase in diameter. Erection straightens the sigmoid flexure. Retractor penis m is very strong.
• b. (i) Bull: Glans penis is complex – urethral orifice is on one side of glans penis.
• c. (ii) Ram: Urethral process ~2 cm long.
• d. Intromission and ejaculation occur during first intromission.

Question 19

outline some comparative anatomy points in the boar

Answer 19

• a. Fibroelastic type with sigmoid flexure (pre-scrotal).
• b. Glans penis is not distinct – is coiled (corkscrew-shaped).
• c. Urethral orifice is slit-like and opens ventro-laterally.

Question 20

outline which animals have ampulla and their relative sizes

Answer 20

• Stallion – very large
• Dog - present but small and covered by the prostate
• Cat - absent
• Bull – very large
• Boar – present but not obvious
• Ram – as bull

Question 21

outline which animals have a prostate gland and their relative sizes

Answer 21

• a. Stallion – is lobulated and lies dorsal to neck of bladder and beginning of urethra. Consists of two lateral lobes and connective isthmus. Numerous ducts enter the urethra near the seminal colliculus.
• b. Dog - is relatively large; is globular and surrounds the neck of the bladder and urethra. There are numerous ducts which enter near the seminal colliculus.
• c. Cat – very small
• d. Bull – composed of body and pars disseminate. Body lies dorsal to neck of bladder and beginning of urethra; measures 4 cm in longitudinal dimension. Pars disseminate surrounds the pelvic part of the urethra; it is concealed by the urethral muscle. Numerous ducts enter the urethra caudal and lateral to the seminal colliculus.
• e. Boar – composed of body and pars disseminate like the bovine. The ducts are similar to the bovine.
• f. Ram – only disseminate component is present.

Question 22

outline which animals have vesicular glands and their relative sizes/shapes

Answer 22

• a. Stallion – elongated piriform sacs on either side of caudal part of bladder, long axis parallel with ductus deferens. Excretory duct empties with ductus deferentes to form ejaculatory orifice. Are 15 - 20 cm long by 5 cm wide in stallion. In gelding are much smaller.
• b. Dog - absent
• c. Cat - absent
• d. Bull – compact glandular organs with lobulated surface-like thick-walled tube bent upon itself in a tortuous manner. Excretory duct empties together with ductus deferens. Are 10 – 13 cm long by 5 cm in diameter and are often asymmetrical.
• e. Boar – exceedingly large and extends into abdominal cavity. Are three-sided pyramidal masses. Lobulated and glandular in structure. May unite with the ductus deferens. Are 13 – 15 cm long by 5 – 8 cm wide.
• f. Ram – present as bull.

Question 23

outline which animals have bulbourethral glands and their relative size/shape

Answer 23

• a. Stallion – they are ovoid in form, somewhat compressed dorsoventrally. The urethral muscle covers the glands. In the stallion they may be 5 cm long, but in the gelding, they are hazelnut size. Six to eight ducts enter urethra caudal to prostatic ducts near the midline.
• b. Dog - absent
• c. Cat - small
• d. Bull – somewhat smaller than in the stallion, are covered by heavy connective tissue and bulbospongiosus muscle. Each gland has a single duct which enters the urethra under cover of a fold of mucous membrane.
• e. Boar – they are large and dense and are somewhat cylindrical. Lie on either side of the caudal 2/3 of the pelvic urethra. In a large boar they may be 13 cm long x 3 cm wide. They are only partially covered by the bulbospongiosus muscle. The surface is lobulated. A large single duct from each gland enters the dorsal part of the urethra near the ischial arch.
• f. Ram – small but similar to bull.

Question 24

Identify seminiferous tubules and Leydig cells

Answer 24

Question 25

Identify the seminiferous epithelium and Leydig cells

Answer 25

Question 26

What other cell type is found in seminiferous tubule?

Answer 26

Sertoli cell – not always easy to identify but extend across the whole spermatogenic epithelium

Question 27

What is the function of Leydig cells and how is this regulated?

Answer 27

Leydig cells produce testosterone under the influence of LH

Question 28

what does the rete testis do

Answer 28

produces most of the testicular fluid which is reabsorbed in the epididymis (head)

Question 29

Identify epididymis ducts and efferent ductules

Answer 29

Question 30

what is the function of the epididymis and how is it regulated

Answer 30

Accumulation, storage and maturation of spermatozoa; making spermatozoa motile; absorption of excess fluid accompanying the spermatozoa from the testis. Development of epididymis is androgen dependent

Question 31

the efferent ductules are lined which which type of epithelium

Answer 31

pseudostratified columnar epithelium
- cuboidal cells with microvilli, columnar cells with cilia

Question 32

the ductus epididymis is lined with what type of epithelium

Answer 32

pseudostratified columnar epithelium, surrounded by loose connective tissue and circular smooth muscle fibres