Reproductive embryology

Question 1

intermdediate (UG) mesoderm

Answer 1

splits to form neprogenic ridge (lateral) and genital ridge (medial)

Question 2

genital ridge

Answer 2

in abdomen, medial to nephrogenic ridge. Forms gonads.

Question 3

nephrogenic ridge

Answer 3

forms mesonephric (Wolfian) duct (forms ureteric bud, kidney, ureter, urinary bladder, male internal reproductive organs) and paramesonephric (Mullerian) duct (female internal reproductive organs)

Question 4

AMH

Answer 4

produced by sertoli cells, suppresses paramesonephric ducts

Question 5

Testosterone

Answer 5

produced by Leydig cells in response to LH or hCG. Stimulates mesonephric duct structures (efferent ductules, epididymis, vas deferens, seminal vesicles) and male secondary sex characteristics

Question 6

DHT

Answer 6

converted from testosterone in peripheral tissue by 5alpha-reductase-2. Promotes development of penis, scrotum, and prostate.

Question 7

hypospadia

Answer 7

penile urethra open on ventral surface of penis. Cause: urethral folds fail to fuse on ventral surface of penis.

Question 8

epispadias

Answer 8

penile urethra opens on dorsal surface of penis. Unknown cause.

Question 9

indirect hernia

Answer 9

failure of processus vaginalis to close around deep inguinal ring.

Question 10

cortex of indifferent gonad

Answer 10

forms ovary

Question 11

medulla of indifferent gonad

Answer 11

forms testis

Question 12

uterus arcuatus

Answer 12

slight indentation in fundus. Cause: lack of fusion of paramesonephric ducts

Question 13

uterus bicornis bicolis

Answer 13

2 uterine bodies, 2 cervixes. Cause: lack of fusion of paramesonephric ducts.

Question 14

uterus didelphis with double vagina

Answer 14

2 uterine bodies, 2 vaginas. Cause: complete lack of fusion of paramesonephric duct.

Question 15

uterus bicornis unicollis

Answer 15

2 uterine bodies, one cervix. Cause: one paramesonephric duct fails to make contact with the other.

Question 16

uterus unicornis

Answer 16

one uterine body, one cervix, one uterine tube. Cause: one paramesonephric duct regesses.

Question 17

Klinefelter syndrome

Answer 17

“girly man syndrome” 47, XXY, male. Testes form, but infertile. At puberty: low testosterone, high estrogen. Secondary female characteristics.

Question 18

Turner syndrome

Answer 18

45, XO, female. No ovaries, streak gonads, cancer risk. Rest of female internal and external genitalia form normally. At puberty: low estrogen, lack of secondary sex characteristics.

Question 19

Swyer syndrome

Answer 19

46, XY, female. Point mutation in SRY gene->defective TDF protein. Very similar presentation to 45, XO (Turner’s syndrome). No ovaries, streak gonads, rest of female external and internal genitalia form normally.

Question 20

True hermaphroditism

Answer 20

most have 46, XX genotype, likely translocated Y chromosome. Development of ovotestes. Internal genitalia most often female, ambiguous external genitalia.

Question 21

Female pseudohermaphroditism

Answer 21

46, XX. Congenital adrenal hyperplasia->excess testosterone. Ovaries form due to lack of TDF. Internal genitalia usually female. Masculinization of external genitalia.

Question 22

Male pseudohermaphroditism

Answer 22

46, XY. Testes form (normal SRY). Insufficient androgen and AMH (hypogonadism). External and internal genitalia female (due to absence of testosterone and AMH).

Question 23

Androgen insensitivity syndrome

Answer 23

46, XY. Female phenotype. Testes form (normal SRY). AMH and testosterone production is normal. Lack of androgen receptor expression on reproductive tissues. Mesonephric AND paramesonephric ducts degenerates (testosterone insensitivity, AMH production)->no female internal genitalia. Female external genitalia form.