Sexual Development Flashcards
Types of sex (x4)
- Genetic: XX and XY
- Phenotypic: appearance
- Gonadal sex: testes + ovaries
- Behavioural: self identification
Indifferent gonads
Outer portion develops into ovaries and the inner portion develops into testes
How does the female reproductive tract get inhibited?
- Testis determining factor stimulates Sertoli cells in the gonad
- These cells make Anti-Mullerian hormone
- Causes the Mullerian duct to regress
How is the male reproductive tract made?
- Leydig cells in the gonad make testosterone
2. Testosterone stimulates the mesonephric ducts to develop into male structures
Embryology of XX phenotype
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
How is the kidney formed?
A bud comes off the mesonephric duct to form the metanephric kidney
Vas deferens goes over the ureter (water under the bridge)
Persistent Mullerian duct syndrome
The paramesonephric duct does not degenerate due to a shortage of anti-Mullerian hormone –> testicles are held up in the abdomen/pelvis (undescended testes)
Inguinal descent of the testes
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)
Why does the inguinal canal have to seal?
Or else the bowel will come down
What is a genital tubercle?
Develops into a penis or clitoris
What is the labioscrotal swelling?
Becomes the labia to seals up + becomes scrotum
What is the processus vaginalis?
Gap made by the inguinal canal
Layers of the tunica vaginalis
Visceral layer: lost peritoneum (on the testicle)
Parietal layer: not on the testicle
Where are the seminiferous tubules found?
In the epidymis
Path of sperm
Testis –> epidymis –> vas deferens –> penis
Hydrocoele
Buildup of serum in scrotal cavity
Hemantocoele
Buildup of blood in scrotal cavity
What happens if the testis do not descend?
Orchiopexy –> pulling testes into scrotum
If the testis stay in abdomen, can become cancerous
Why are the male gonads outside of the body?
Spermatoza will only develop at 2-3 degrees below body temp.
Testes move up + down to maintain this temp.
Upward movement of the testes
Done by the striated cremaster muscle (extension of the internal oblique)
Compression of the scrotum
Done by the smooth dartos muscle
How do we get testes to be a cooler temp?
Relaxation of the cremaster and dartos muscles
Purpose of the pampiniform plexus
Surrounds the gonadal artery
Cools the incoming warm blood (allows for cool blood –> testes)
Why do inguinal hernias occur?
Inguinal canal had to stay open –> weak point in the abdominal wall
Direct vs indirect hernias
Direct: went through the abdominal wall to the inguinal canal (later on in life)
Indirect: goes through the inguinal canal (seen in newborns)
What do the urogenital folds develop into?
Female: labia minora, vestibule & part of the urethra
Male: seal under the influence of androgens
What is the midline raphe?
Line of fusion of where the scrotum joins together
What is intersex?
Having both male and female sexual characteristics
What is XX intersex?
Chromosomally female with male genitalia
Due to the androgens
The male hormones (mostly testosterone) arises due to overactive adrenal gland
= Congenital adrenal hyperplasia
What is XY intersex?
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
