Embryology Flashcards
- Review the processes of conception, implantation, and placental development
- Describe the development of the early embryo, including how multiple pregnancies occur
- Review the development of the urinary system and its links to the development of the reproductive system in males and females
- Describe the embryology of germ cell migration and the formation of the indifferent gonad
- Describe the development of the testis and the male reproductive tract
- Describe the development of the female reproductive tract
- Discuss the basis of some common anomalies of the reproductive system
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Which part of mesoderm forms the urogenital system (urinary and reproductive)
Intermediate plate mesoderm
At about 6 weeks, what happens to the mesonephros
Medial part of mesonephric ridge thickens to form the genital/ gonadal ridge
Once the genital ridge has formed, what happens (still week 6)
Germ cells migrate from yolk sac and embed into the primitive sex cords of the genital ridges to form an INDIFFERENT GONAD
What is the paramesonephric duct
Epithelium of the mesonephros invaginates to form a tube, becoming the paramesonephric duct
Mesonephric and paramesonephric duct also known as
Mesonephric - wolffian
Paramesonephric - mullerian
In males, what happens to the
- indifferent gonad
- mesonephric duct
- paramesonephric duct
Gonad forms testis
Mesonephric duct develops into epididymis, vas deferens, seminal vesicle,
Paramesonephric duct degenerates
In females, what happens to the
- indifferent gonad
- mesonephric duct
- paramesonephric duct
- urogenital sinus
Gonad forms the ovary
Mesonephric duct degenerates
Paramesonephric duct forms fallopian tube, uterus, cervix, part of vagina
Urogenital sinus forms bladder and lower vagina
How does the indifferent gonad know whether to develop into a testes or an ovary
A region on Y chromosome will code for the SRY gene which induces it to develop into a testes as SRY encodes for TDF (testis determining factor)
Female foetus has no SRY region so no TDF so by default develops into ovaries
What is the thick capsule called around the testes
Tunica alguien
Male sex glands
- seminal vesicles
- prostate
What are they outgrowths of embryologically
Seminal vesicle - outgrowth from caudal end of mesospheric duct
Prostate - outgrowth from urethra
About 2 million primordial follicles at birth but many become atretic before puberty
After puberty, hormones stimulate 12-15 follicles per cycle to develop but…
ONLY ONE MATURES AND OVULATES
Where do the tubular components (i.e. fallopian tubes) of the female reproductive system come from
Absence of testosterone causes degeneration of the mesonephros and mesosphrenic duct
Paramesonephric duct then gives rise to female genital tract
Cranial end of paramesonephric duct –>
Caudal end of “ “ –>
Uterus + superior vagina
Gonads initially form in what region
Lumbar
