Sexual Development

Question 1

Types of sex (x4)

Answer 1

1. Genetic: XX and XY
2. Phenotypic: appearance
3. Gonadal sex: testes + ovaries
4. Behavioural: self identification

Question 2

Indifferent gonads

Answer 2

Outer portion develops into ovaries and the inner portion develops into testes

Question 3

How does the female reproductive tract get inhibited?

Answer 3

1. Testis determining factor stimulates Sertoli cells in the gonad
2. These cells make Anti-Mullerian hormone
3. Causes the Mullerian duct to regress

Question 4

How is the male reproductive tract made?

Answer 4

1. Leydig cells in the gonad make testosterone

2. Testosterone stimulates the mesonephric ducts to develop into male structures

Question 5

Embryology of XX phenotype

Answer 5

Outer part of indifferent gonads develops into an ovary

Mullerian duct becomes the Fallopian tube (the ducts fuse to become uterus, cervix & vagina)

Ovary descends into pelvis

Note: there is no anti-AMH hormone –> small remnants of mesonephric ducts stay

Question 6

How is the kidney formed?

Answer 6

A bud comes off the mesonephric duct to form the metanephric kidney

Vas deferens goes over the ureter (water under the bridge)

Question 7

Persistent Mullerian duct syndrome

Answer 7

The paramesonephric duct does not degenerate due to a shortage of anti-Mullerian hormone –> testicles are held up in the abdomen/pelvis (undescended testes)

Question 8

Inguinal descent of the testes

Answer 8

Descent of testes into scrotum must occur through the inguinal canal

Gubernaculum pulls testes through deep ring (abdomen) and out of the superficial ring (scrotum)

When this happens, a little fold of peritoneum also gets pulled down (transversals fascia)

Question 9

Why does the inguinal canal have to seal?

Answer 9

Or else the bowel will come down

Question 10

What is a genital tubercle?

Answer 10

Develops into a penis or clitoris

Question 11

What is the labioscrotal swelling?

Answer 11

Becomes the labia to seals up + becomes scrotum

Question 12

What is the processus vaginalis?

Answer 12

Gap made by the inguinal canal

Question 13

Layers of the tunica vaginalis

Answer 13

Visceral layer: lost peritoneum (on the testicle)

Parietal layer: not on the testicle

Question 14

Where are the seminiferous tubules found?

Answer 14

In the epidymis

Question 15

Path of sperm

Answer 15

Testis –> epidymis –> vas deferens –> penis

Question 16

Hydrocoele

Answer 16

Buildup of serum in scrotal cavity

Question 17

Hemantocoele

Answer 17

Buildup of blood in scrotal cavity

Question 18

What happens if the testis do not descend?

Answer 18

Orchiopexy –> pulling testes into scrotum

If the testis stay in abdomen, can become cancerous

Question 19

Why are the male gonads outside of the body?

Answer 19

Spermatoza will only develop at 2-3 degrees below body temp.

Testes move up + down to maintain this temp.

Question 20

Upward movement of the testes

Answer 20

Done by the striated cremaster muscle (extension of the internal oblique)

Question 21

Compression of the scrotum

Answer 21

Done by the smooth dartos muscle

Question 22

How do we get testes to be a cooler temp?

Answer 22

Relaxation of the cremaster and dartos muscles

Question 23

Purpose of the pampiniform plexus

Answer 23

Surrounds the gonadal artery

Cools the incoming warm blood (allows for cool blood –> testes)

Question 24

Why do inguinal hernias occur?

Answer 24

Inguinal canal had to stay open –> weak point in the abdominal wall

Question 25

Direct vs indirect hernias

Answer 25

Direct: went through the abdominal wall to the inguinal canal (later on in life)

Indirect: goes through the inguinal canal (seen in newborns)

Question 26

What do the urogenital folds develop into?

Answer 26

Female: labia minora, vestibule & part of the urethra

Male: seal under the influence of androgens

Question 27

What is the midline raphe?

Answer 27

Line of fusion of where the scrotum joins together

Question 28

What is intersex?

Answer 28

Having both male and female sexual characteristics

Question 29

What is XX intersex?

Answer 29

Chromosomally female with male genitalia

Due to the androgens

The male hormones (mostly testosterone) arises due to overactive adrenal gland

= Congenital adrenal hyperplasia

Question 30

What is XY intersex?

Answer 30

Chromosomally male with female genitalia (micropenis, no testes in scrotum etc)

Usually because of an inadequate or insensitivity to male hormones (don’t make androgens or don’t have the receptors for them)

= Androgen insensitivity syndrome (receptors don’t work)

Typically no female internal organs (bc of AMH) –> only short blind-ended vagina

Phenotypically female in adulthood