Sexual Differentiation

Question 1

Function of SRY

Answer 1

1. Blocks ovary formation

2. Stimulate testicular formation

Question 2

Function of Sertoli cells in sexual differentiation

Answer 2

Produce AMH = regression of paramesonephric ducts (Mullerian ducts) that develop into uterine tubes and uterus

Question 3

Function of Leydig cells in sexual differentiation

Answer 3

Produce testosterone – masculinization of Wolffian ducts (mesonephric ducts) into seminal vesicles, ductus deferens, epididymis

Question 4

Function of DHT in sexual differentiation

Answer 4

Masculinization of internal structures into external structures:

1. genital tubercle to penis
2. labioscrotal folds to scrotum
3. urogenital sinus to prostate

Question 5

Consequences of 5alpha-reductase 2 deficiency

Answer 5

No conversion of testosterone –> DHT = appears female genitalia externally
- but at puberty, 5alpha-reductase 1 is expressed and masculinizes the genitalia

conversion of female at birth to male at puberty

Question 6

Consequences of complete androgen insensitivity regarding:

1. Sertoli cells
2. Leydig cells
3. Why does a short vagina still develop?
4. What happens at puberty?

Answer 6

1. Sertoli cells still produce AMH (not under control of androgen receptors) = regression of paramesonephric ducts = NO INTERNAL FEMALE REPRODUCTIVE STRUCTURES
2. Leydig cells produce testosterone but no androgen receptors = regression of Wolffian duct = NO MALE INTERNAL REPRODUCTIVE STRUCTURES
3. Short vagina develops (derived from urogenital sinus) – remember that the vagina is derived from 2 sources
4. Conversion of testosterone to estradiol = growth spurt and breast development

46, XY female

Question 7

Describe mosaicism during gonadal intersex

Answer 7

Fusion of XX egg with Y sperm of X egg with XY sperm

- mix of both 46 XY and 46 XX = development of both ovaries and testis