Repro: Development Of The Repro Tract

Question 1

What components make up the male and female internal genitalia?

Answer 1

Males:
Testis, duct system, seminal vesicles, prostate and bulbs-urethral glands

Females:
Ovaries, fallopian tubes, uterus, cervix, vagina

Question 2

What are some of the secondary sexual characteristics?

Answer 2

Males: facial and pubic hair, increased muscle mass, deepened voice

Females: breast development, subcutaneous fat to support pregnancy, pubic and underarm hair

Question 3

What’s the urogenital ridge and what structures does it contain?

Answer 3

A region of intermediate mesoderm giving rise to the embryonic kidney and gonad
Contains: indifferent gonad and primordial germ cells (extra gonadal) - have to move into the gonad

Question 4

What is the route the primordial germ cells have to take to reach the gonad?
What is a possible complication of this?

Answer 4

They arise in the yolk sac and migrate to the retroperitoneum along the dorsal mesentery
Cells can get deposited along the way causing germ cell tumours

Question 5

How does the tunica albuginea differ in the female and male gonad?

Answer 5

In the male gonad it is thick and fibrous whereas in the female it regresses - the oocytes need to burst through

Question 6

What is the fate of the mesonephric ducts in males and females?

Answer 6

Both sexes: mesonephric ducts reach urogenital sinus and sprout the ureteric bud. The mesonephric duct makes its own opening into the sinus.

Male: the mesonephric duct forms the vas deferens
Female: the mesonephric duct has no purpose so regresses

Question 7

In which sex does the paramesonephric duct remain?

Answer 7

Also called the Müllerian duct

Remains in the female to form the duct system

Question 8

What are the signals ensuring the correct duct remains?

Answer 8

XY embryo:
Testis develop which secrete androgens to support the mesonephric duct.
Testis secrete mullerian inhibiting hormone which causes paramesonehric duct to regress

XX embryo:
Ovaries develop so no androgens to support mesonephric duct, no mullerian inhibiting hormone to regress paramesonephric duct.

Question 9

Describe the indifferent stage of the external genitalia and state which components form the genitalia in each sex

Answer 9

Genital tubercle: glans of penis in males, clitoris in females
Genital folds: fuse in males to form spongy urethra, no fusion in females so forms vestibule
Genital swellings: form scrotum in males, and labia majoria