Reproductive Development Flashcards
What causes the retention of the mesenephric ducts in the male?
-testosterone produced by the interstial cells of the rete cords
What is the origin of the reproductive system? How is the embryo bipotential?
- mesodermal in origin
- gonads arise by proliferation of epithelium along the mesonephric ridge
- embryonic gonad is a neutral gonad which has potential to form testis or ovary
- embryo has both Mullerian and Wolffian ducts
How is the bipotential system determined?
-presence or absence of SRY
Describe the structure of the indifferent gonad.
- outer cortex and an inner medulla
- within medulla, solid cords of cells develop -> sex cords
-separating the cortex from the medulla is a CT layer called the tunica albuginea
+in the adult gonad, the tunica albuginea will lie on the external surface of the testis but will be internalized in the ovary
What do the sex cords give rise to?
- seminiferous tubules containing Sertoli cells and interstitial cells in the event of a male
- anastomosing with the sex cords in the genetic male are the rete cords
- in a female the medulla regresses and the cortex forms the ovary
What will the rete cords turn into?
-in the female, the rete cords will degenerate along with the rest of the medulla but some vestigial mesonephric tubules may be retained
-in males, the mesonephric tubules will be retained as part of the closed duct system that conveys sperm to the exterior.
+retained mesonephric tubules are called efferent ductules
How does the female system form?
- cortex forms ovary
- rete cords and sex cords will degenerate along with the mesonephric tubules adn ducts
- the Müllerian ducts will give rise to the oviducts, uterus, and a portion of the vagina
- to form the uterus, the Müllerian duct fuses distally
What is a bipartite uterus?
-uteri remain unfused and two uteruses remain
What is a bicornuate uterus?
-uterus worth two prominent horns
What is a simplex uterus?
-single uterus -> human and primate uterus
What do the proximal ends of the Müllerian ducts form?
-become expanded as the Ostia of the oviducts
When eggs are ovulated they are released from the Graafian follicles and almost immediately enter the Ostia and begin their journey.
:)
Where are the ovaries and testes positioned in the abdomen?
- ovaries retain their abdominal position in all vertebrates
- testes retain their abdominal position in poikilotherms, but run into problems of overheating in homeothermic birds and mammals
How is testicular overheating prevented in humans?
-testes moved out of abdominal region into the scrotal sacs
How do external genitalia start?
-bipotential structures
