S2.2 Development Of The Tracts

Question 1

In which germ layer do kidney and gonads develop?

Answer 1

Intermediate mesoderm

Question 2

The repro, urinary and GI tracts share what common caudal opening?

Answer 2

The hindgut ends in the cloaca

Question 3

Describe the function of primordial germ cells

Answer 3

PGC arise in the wall of the yolk sac
They migrate to the gonadal ridge giving us gametes.
Y chromosome has SRY region producing the testes, females don’t have this so produce ovaries

Question 4

Describe the formation of male internal genitalia

Answer 4

Testes produce ACH
Androgens maintain the medonephric/wollfian ducts, which move closer forming the epididymis, vas deferens and seminal vesicle

Question 5

Describe the formation of female internal genitalia

Answer 5

The ovary doesn’t produce androgens

Paramesonephric/Müllerian duct therefore dominates forming the uterus, cervix, 1/3 vagina

Question 6

Where do the genital ducts end?

Answer 6

At the urogenital sinus part of the cloaca

Question 7

What maintains the wolffian duct?

Answer 7

Testes produce MIH

Testes also produce androgens and testosterone for support of the wolffian duct

Question 8

What maintains the Müllerian duct?

Answer 8

Females don’t have testes so no MIH produced, also no androgen production so wolffian duct shall degenerate

Question 9

What does the urogenital sinus become?

Answer 9

Males - bladder and prostate

Females - bladder and lower vagina

Question 10

Describe the affects of exogenous androgen sources in a female

Answer 10

Wolffian duct shall be supported by androgens
No testes to produce MIH
Therefore both ducts develop

Question 11

Describe the affects of androgen insensitivity syndrome

Answer 11

Testosterone receptors don’t work so wolffian duct regresses.
Testes still produce MIH so no Müllerian duct either

Question 12

In the male, describe the development of the external genitalia

Answer 12

Genital tubercle - glans penis
Genital folds - spongy urethra
Genital swellings - scrotum

Question 13

In the female, describe the development of the external genitalia

Answer 13

Genital tubercle - clitoris
Genital folds - labia minora
Genital swellings - labia majora

Question 14

Describe the descent of the testis

Answer 14

Testes are attached to the gubernaculum
Processes vaginalis leads the way for testes to follow
Testes reach the scrotum and processes vaginalis closes up

Question 15

Describe the decent of the ovaries

Answer 15

Gubernaculum attaches to ovaries
Ovaries descend to pelvis
Uterus has developed which prevents further descent
Gubernaculum becomes ovarian and round ligament