Reproductive System (embryology)

Question 1

What do Leydig cells secrete?

Answer 1

Testosterone

Question 2

What doe Sertoli cells secrete?

Answer 2

Mullerian inhibiting hormone (MIH)

Question 3

Female genitalia develop by __________, meaning in the absence of ________ and _________

Answer 3

1. Default
2. Testosterone
3. MIH

Question 4

Male genitalia development

Answer 4

1. XY chromo has SRY gene –> leydig and sertoli cells
2. Leydigs secrete T and Sertoli secretes MIH
3. T causes differentiation of mesonephric ducts into male ducts
4. MIH causes regression of Mullerian duct

Question 5

Female genitalia development

Answer 5

1. XX chromo
2. Mesonephric duct fail to develop (no T)
3. Mullerian ducts differentiate into female ducts (no MIH)

Question 6

Differentiation of indifferent gonad into testis

Answer 6

With Y influence:
1. Medullary cords develop
2. No cortical cords
3. Thick tunica albuginea

Question 7

Differentiation of indifferent gonad into ovary

Answer 7

Absence of Y:
1. Medullary cords degenerate
2. Cortical cords develop
3. No tunica albuginea

Question 8

What does the differentiation of mesonephric ducts and external male genitalia depend on?

Answer 8

Depends on T and DHT (5a reductase converts T into DHT), respectively

Question 9

Where do gonads develop from?

Answer 9

Genital ridge, thickened intermediate mesoderm

Question 10

What cells do gonads contain?

Answer 10

Germ cells and supporting cells

Question 11

Primordial germ cells

Answer 11

Arise from yolk sac and migrate along the gut wall into the genital ridge
Proliferate and get into the sex cords (medullary in males, cortical in females)

Question 12

Medullary cords in males

Answer 12

Differentiate into seminiferous cords with:
1. Primordial germ cells –> spermatogonia
2. Supporting cells–> sertoli (MIH)

Question 13

Cortical cords in females

Answer 13

Contain primary oocytes surrounded by follicular cells
primordials differentiate into oogonia and have entered meiosis 1

Question 14

What do mesonephric tubules turn into in males?

Answer 14

Efferent ductules

Question 15

What do mesonephric ducts turn into in males?

Answer 15

Epididymus, ductus deferens, ampulla, ejaculatory duct, seminal vesicle

Question 16

What does the urogenital sinus develop into in males?

Answer 16

Urethra –> bulbourethral glands and prostate

Question 17

___________ is the remnant of the cranial end of the mesonephric duct in males

Answer 17

Appendix epididymus

Question 18

What does the paramesonephric duct turn into in females?

Answer 18

Uterus, cervix, cranial 1/3 of the vagina

Question 19

The remaining vagina and vestibule develop from ___________

Answer 19

urogenital system

Question 20

What are remnants of the mesonephric tubules of females?

Answer 20

Epoophoron and Paroophoron

Question 21

Gartner’s cyst

Answer 21

Remnant of the mesonephric duct
Found in vestibule or vagina
Prone to become a cyst

Question 22

Where does the male external genitalia develop from?

Answer 22

Three swellings:
Genital tubercle –> penis
Bilateral urethral folds –> penile urethra
Bilateral scrotal swelling (genital) –> scrotum

Question 23

Finasteride/ DHT blocker

Answer 23

Used to treat hair loss, prostate hypertrophy and contraindicated in pregnant women

Question 24

Where does the female external genitalia develop from?

Answer 24

Genital tubercle –> clitoris
Bilateral urethral folds –> labia of vulva
Urethral groove –> opens and forms vestibule
Bilateral scrotal swelling (genital) –> degenerate

Question 25

Hermaphrodite

Answer 25

Genital organs of both sexes present
True hermaphrodite rare (with both male and female gonads)

Question 26

Pseudo-hermaphrodite

Answer 26

Most common form (esp. in dogs)
Have gonads of one sex and genital organs with some characteristics of both sexes
Male: testes with some female genitalia
Female: Ovary with some male genitalia

Question 27

Klinefelter Syndrome (XXX, 47 chromos)

Answer 27

In cats (tricolor cat), dogs, boars, bulls
Testis atrophy, spermatogenesis inhibited, T present @ low concentration

Question 28

Cryptorchidism

Answer 28

Intra-abdominal or inguinal retention of one of both testes (inherited condition)

Question 29

Freemartin disease

Answer 29

Females born as twin to males and transfer T and MIH from males to females

Question 30

External and internal genitalia in free martin

Answer 30

Female-like (vagina is under developed)
Some development of epididymus, ductus deferens and seminal vesicle
Some underdevelopment of the uterus and vagina

Question 31

Hypospadias and Epispadias

Answer 31

Abnormal fusion of the urethral folds on the ventral side of the penis
… dorsal side

Question 32

Androgen insensitivity syndrome (46, XY)- Testicular feminization, male pseudo-hermaphrodite

Answer 32

Testes present and produce androgens but androgen receptors lacking
External genitalia fail to masculinize and develop as short blind vagina
Male ducts underdeveloped and female ducts absent

Question 33

Congenital Adrenal Hyperplasia (Female pseudo-hermaphrodite)- 46, XX

Answer 33

Absence of adrenal cortical hormone gene –> overproduction of adrenal androgens
External gen: male like
Internal gen: Female ducts fully develop, male ducts partially developed