Development and Sexual Differentiation of the Reproductive System

Question 1

What is the ‘mesonephros’ in foetal development?

Answer 1

It is the tissue that will later form the kidneys later in development

Question 2

What are gonadal ridges and where are they found?

Answer 2

They are masses of mesoderm which form bulges on the abdominal wall (medial to mesonephros) which eventually forms the testes or ovaries

Question 3

At which stage of development are foetus’ sexually indifferent?

Answer 3

Week 5

Question 4

What are Müllerian ducts?

Answer 4

Tissue that will differentiate into oviducts in females, and these develop laterally to the Wolffian ducts and are paramesonephric

Question 5

What are the Wolffian ducts?

Answer 5

These ducts will develop into the vas deferens in males and this is a mesonephric tissue

Question 6

What is the common cloaca?

Answer 6

This is a structure that is present at the sexually indifferent stage of development, whereby both the Urogenital and GI systems feed into a common tract

Question 7

At what week of development does sexual differentiation begin?

Answer 7

7-8 weeks

Question 8

Describe the beginning of male sex differentiation

Answer 8

The seminiferous tubules form in the gonadal ridge and then join the Wolffian duct (which eventually becomes vas deferens). The testes have begun to develop and secrete anti-Müllerian hormone to cause the degeneration of the Müllerian ducts

Question 9

Describe the beginning of female sex differentiation

Answer 9

Müllerian ducts start to differentiate into the oviducts, the Wolffian ducts degenerate.

Question 10

Describe the descent of the ovaries in female sex differentiation

Answer 10

The ovaries descend on the gubernaculum from the posterior abdominal wall to the pelvic brim, where the descent is then stopped by the presence of the broad ligament

Question 11

Describe how the gubernaculum in ovarian descent differentiates into two different ligaments

Answer 11

The descent is stopped by the presence of the broad ligament, and this causes the cranial gubernaculum to become the ovarian ligament and the caudal gubernaculum to become the round ligament

Question 12

What is the inguinal canal?

Answer 12

This structure is approximately 4cm long and it begins at the deep inguinal ring and emerges at the superficial inguinal ring

Question 13

How come both genders have an inguinal canal?

Answer 13

Due to the presence of a sexually indifferent stage in development

Question 14

Describe the development of the inguinal canal

Answer 14

A gubernaculum descends on each side of the abdomen from the inferior pole of the gonad, then travels obliquely through anterior abdominal wall, and attaches caudally to the internal surface of the labioscrotal swellings

Question 15

What is meant by the ‘labioscrotal swelling’

Answer 15

The tissue that will eventually become either the scrotum or labia majorum

Question 16

What is the processus vaginalis?

Answer 16

This is an invagination of the peritoneum which develops anterior to the gubernaculum, and then herniates through the abdominal wall along the path formed (by gubernaculum). This structure carries extensions of the layers of the anterior abdominal wall (which form walls of inguinal canal)

Question 17

When does gonadal development begin?

Answer 17

Week 5 of development (masses of mesoderm, AKA gonadal ridges)

Question 18

When do the testes begin to descend?

Answer 18

Around 26 weeks or 7 months

Question 19

Describe the function of the gubernaculum in the descent of testes in a male

Answer 19

Gubernaculum is attached to the testes and the inferior pole of the scrotum (swelling) and works to pull the testes down from peritoneum into scrotum. Vas deferens descends alongside as well as neurovascular supply from posterior abdominal wall.

Question 20

What is cryptorchidism?

Answer 20

Known as hidden testes, when the testes haven’t descended at birth and remain within peritoneum

Question 21

What are ectopic testes?

Answer 21

Very rare condition when the gubernaculum doesn’t attach to base of scrotum swelling, but does so elsewhere

Question 22

What is a congenital inguinal hernia (indirect)?

Answer 22

If space between tunica vaginalis and peritoneal cavity fails to close, persistent processus vaginalis exists and a loop of intestine may herniate through this region, passing through deep inguinal ring to inguinal canal

Question 23

What is hydrocele?

Answer 23

when the vaginal process (males) remains open, but is too small to allow herniation, but there is accumulation of peritoneal fluid in either spermatic cord or testes

Question 24

Describe the arterial supply to the testes

Answer 24

Testicular artery arises from abdominal aorta

Question 25

Describe the venous drainage of the testes

Answer 25

By testicular vessels, the left hand side feeds into the left renal vein, whereas the right side drains into the inferior vena cava

Question 26

Describe the path of the vas deferens

Answer 26

Part of spermatic cord, so passes through inguinal canal –> runs on lateral pelvic wall (covered by peritoneum) –> crosses external iliac vessels –> crosses ureter –> reaches spine –> descends behind bladder –> dilated ampulla of vas then joined by seminal vesicles at common ejaculatory duct

Question 27

Describe the seminal vesicles

Answer 27

coiled sacs part of the distal part of the vas deferens. which is separated from rectum (which lies posterior to vesicles) by the rectovesical fascia and rectovesical pouch

Question 28

Why don’t vasectomies work immediately?

Answer 28

Still sperm stored in seminal vesicles so potential for fertility 3-6 months later

Question 29

Describe the structure of the prostate

Answer 29

Lies below the bladder on the pelvic floor and consist of 1 median and 2 lateral lobes - transversed by urethra and ejaculatory duct

Question 30

What might prostatic hypertrophy indicate?

Answer 30

Usually growth of the median lobe which disturbs vesicular sphincter action, so urinating is difficult. However, if there is growth of the lateral lobes this is likely to be indicative of cancer of the prostate and will be palpable upon rectal examination

Question 31

What may cause the development of a double, bicornuate or unicornuate uterus?

Answer 31

Incomplete fusion of the mullerian ducts inferiorly, incomplete development of the ducts, failure of one of the ducts.

Question 32

What are the three main ligaments of the uterus?

Answer 32

Ovarian ligament (ovary to uterus), round ligament (uterus to labium majorum) and broad ligament (sheet of peritoneum acting as suspensory ligament)

Question 33

How are the ovaries attached to the broad ligament?

Answer 33

At the back by the mesovarium

Question 34

Name the 5 structures which support the uterus

Answer 34

1) Levator ani muscle (pelvic floor)
2) Perineal body (insertion point of many support muscles)
3) Transverse cervical ligaments (lateral pelvic walls to cervix and upper vagina)
4) Pubocervical ligaments (two bands of CT from pubis to cervix)
5) Sacrocervical ligament (cervix to sacrum)

Question 35

Name the two peritoneal pouches in a female

Answer 35

Vesicouterine pouch (between bladder and uterus) and rectouterine pouch (pouch of Douglas)

Question 36

Where would you find the vesicouterine pouch?

Answer 36

Space between the uterus and the bladder

Question 37

Where would you find the pouch of Douglas?

Answer 37

Between the uterus and the rectum (also known as rectovesical pouch, as in males this would have the seminal vesicles here)

Question 38

Describe the structure of the vagina

Answer 38

Upper half is above pelvic floor and low part is within perineum

Question 39

Describe the fornices of the vagina

Answer 39

Anterior fornix: bladder and urethra here
Posterior fornix: pouch of Douglas
Lateral fornix: ureters, levator ani, urogenital diaphragm and bulb of vestibule

Question 40

Describe the support of the upper vagina

Answer 40

Transverse cervical, pubocervical and sacrocervical ligaments

Question 41

Describe the support of the middle vagina

Answer 41

Levator ani muscles and urogenital diaphragm

Question 42

Describe the support of the lower vagina

Answer 42

Perineal body action

Question 43

Describe the path of the ureters

Answer 43

Pass over bifurcation of common iliac arteries in from of SI joint, then run on lateral pelvic walls and curve forwards and medially opposite the ischial spine and then enter the bladder obliquely.