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Flashcards in Reproductive Development Deck (21)
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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


What are the three primordia that give rise to external genitalia?

-genital tubercle

-genital folds

-genital swellings


What will the genital tubercle form?

Females: clitoris

Males: glans penis


What do the genital folds form?

Females: labia minora

Males: shaft of the penis


What will the genital swellings form?

Females: labia majora

Male: scrotum


What happens when the primordial germ cells don't migrate into the gonads?

-sterile individual


How does SRY influence maleness?

-SRY gene causes the developing Sertoli cells in the sex cords to secrete Mullerian inhibitory factor
+regression of Müllerian ducts