Reproductive embryology

Question 1

What does the SRY (sex determining region of the Y chromosome) initiate the production of?

Answer 1

Testis- determining factor

Question 2

What germ layer do both the urinary and reproductive systems arise from?

Answer 2

The intermediate mesoderm

Question 3

What ridge does the intermediate mesoderm form in the initial development of the urinary and reproductive systems?

Answer 3

Urogenital ridge

Question 4

What are the primitive sex chords?

Answer 4

Found in the indifferent gonad at 5-6 weeks

Formed from the proliferating epithelium of the indifferent gonad which penetrates the underlying mesoderm

Question 5

Where do primordial germ cells migrate from to the urogential ridge in week 6?

Answer 5

Definitive yolk sac

Question 6

What happens if the primordial germ cells dont migrate?

Answer 6

Indifferent gonad develops no further

Question 7

What are the medullary chords?

Answer 7

When the indifferent gonad divides into the 2 distinct region, the outer cortex and the inner medulla, the primitive sex chords detach from the cortex to form the medullary chords

Question 8

What determines what happens to the medullary chords and the cortex in the indifferent gonad?

Answer 8

Presence of TDF

Question 9

What happens to the indifferent gonad in the presence of TDF?

Answer 9

Medullary cords develop
No cortical cords develop
Thick tunica albuginea develops

Question 10

What happens to the indifferent gonad in the absence of TDF?

Answer 10

Medullar cords degenerate
Cortical cords develop
No tunic albuginea develops

Question 11

In the testis as the medullary cords continue to develop what do they form near the hilum?

Answer 11

The rete testis

Question 12

What is the tunica albuginea?

Answer 12

Connective tissue layer around the testis

Question 13

What do the remaining medullary cords in the testis form?

Answer 13

The seminiferous tubules which produce spermatoazoa

Question 14

What do the primordial germ cells give rise to?

Answer 14

Oocytes or spermatazoa

Question 15

What are the cortical cords in the ovaries?

Answer 15

Medullary cords degenerate and epithelium begins to proliferate and produces a second generation of cords called the cortical cords
Cortical cords then split and surround the oocyte

Question 16

At how many weeks do. the gonads become distinguishable?

Answer 16

7

Question 17

What is the gubernaculum?

Answer 17

thickening of the parietal peritoneum

In the male it shortens to facilitate the descent of the testes

Question 18

For which months do the testes remain at the deep inguinal ring?

Answer 18

3 - 7 months

Question 19

What pulls the testes through the inguinal canal and into the scrotum?

Answer 19

The shortening of the gubernaculum with the aid of the increased intra abdominal pressure from the growing abdominal organs

Question 20

What is the process vaginalis and what does it give rise to in the adult?

Answer 20

Pulled down pouch of peritoneum

Gives rise to tunic vaginalis around testis

Question 21

When should the process vaginalis obliterate in a baby?

Answer 21

Within the first year

Question 22

What can a patent process vaginalis lead to?

Answer 22

• If it remains open to the abdominal cavity it can lead to an indirect inguinal hernia
• If it is not open to the abdominal cavity can form cysts which become filled with fluid (as made from peritoneum can produce peritoneal fluid) and can swell - hydrocele

Question 23

What is hydrocele transillumination?

Answer 23

Cysts formed from patent process vaginalis containing fluid (hydrocele) with allow light to pass through easily

Question 24

What are the symptoms of hydrocele and how can it be solved?

Answer 24

Benign - large cysts can cause discomfort

These can be removed surgically

Question 25

What is cryptorchidism?

Answer 25

Failure of one or both of the testis to descend

Question 26

What is cryptorchidism associated with increased risks of?

Answer 26

Testicular cancer and infertility

Question 27

How is cryptorchidism cured?

Answer 27

Affects 1-4% of births but most spontaneously descend within 3 months, those that dont are corrected surgically within 4-6 months

Question 28

Where do the ovaries descend to in the female?

Answer 28

Pelvic brim

Question 29

Where does the gubernaculum insert?

Answer 29

Labia majora

Question 30

What does the gubernaculum persist as in the adult?

Answer 30

From ovary to uterus = ovarian ligament

From uterus through inguinal canal to labia majora = round ligament