UG Development 3 Flashcards

Identify the common male/female primordia at the 8-week "indifferent stage" and the adult UG structures they become.

1
Q

What is the sexually indifferent stage?

A

At 8 weeks, all embryos have a single, common set of UG structures.

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2
Q

What are the common structures at the indifferent stage?

A
  • metanephros
  • mesonephros
  • gonads attached medially to the mesonephros (from the genital ridges)
  • mesonephric (wolffian) ducts
  • paramesonephric (mullerian) ducts
  • UG sinus
  • genital tubercle (phallus)
  • labioscrotal folds
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3
Q

What do the following develop into?

Medulla of primitive gonads?

Primary sex cords?

Cortex of primitive gonads?

Secondary sex cords?

A
  • Medulla - testis, diminishes in females
  • Primary sex cords - seminiferous tubules, disappear or retained as rete ovarii
  • Cortex of primitive gonads - ovary
  • Secondary sex cords - epithelial ovarian follicles surrounding the oocytes
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4
Q

What happens to the mesonephric duct and paramesonephric duct in males?

A
  • Mesonephric duct - retained as ductus deferens and epididymus
  • Paramesonephric duct - disappears
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5
Q

What happens fo the following structures in the female?

Paramesonephric ducts?

Mesonephric ducts?

A
  • Paramesonephric ducts
    • uterine tubes
    • uterus
    • upper part of vagina
      • lower part derived from extension of endoderm of the UG sinus - sinovaginal bulbs form a solid vaginal plate
  • Mesonephric ducts
    • ducts and tubules disappear
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6
Q

What happens when the paired paramesonephric ducts fail to use in a female?

A

vertical septae in the uterus/vagina or double uterus (bicornuate or Didelphys if complete)

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7
Q

What happens in a female when there is agenesis of one or both paramesonephric ducts?

A

unicornate uterus or complete absence of the uterus/vagina

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8
Q

In the male, what is the role of the fibrous gubernaculum?

A
  • Guides descent of the testis through the deep body wall via the inguinal canal
  • Descends behind the processus vaginalis (pouch of parietal peritoneum)
  • Pinches off as the tunica vaginalis testis - coelomic sac that envelops the testis with visceral and parietal layers
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