Reproductive System Development - Articulate Flashcards
Major and minor calices develop, Kidneys begin to ascend, Nephrons begin to form, they will connect to collecting tubules and function by 10 weeks
Week 6-7
Urogentital ridges form from the intermediate mesoderm, and germ cells migrate from the gut wall. Ureteric buds have entered the metanephric mesoderm.
Week 5
The “indifferent” stage with identical primordia in both sexes
2 months
In males, primary sex cords from seminiferous tubules. In females, secondary sex cords from ovarian follicles
10-12 weeks
External genitalia develop
3 months
Testes pass through the inguinal canal into the scrotum
8-9 months
What is the urogenital system divided into
Urinary system & reproductive (genital system)
Where do the Urinary and reproductive system develop from?
Intermediate mesoderm
Intermediate mesoderm swells to form the
Urogenital ridge
What does the urogenital ridge differentiate into?
Genital ridge & Nephrogenic cord/ridge
Formation & differentiation of gonads begins with arrival of
Primordial germ cells
Where do primoridal germ cells enter to begin gonad formation
intermediate mesoderm
rimordial germ cells migrate from wall of the yolk sac, along the dorsal mesentery of the hindgut
4th week
Primordial germ cells arrive at primitive gonads
5th week
Primoridal germ cells invade genital ridges
6th week
What happens if the germ cells fail to reach the ridges?
Gonads do not develop
When is the sex of the embryo genetically determined
At the time of fertilization
Gonads begin as pair of longitudinal ridges
Genital (gonadal) ridges
How are the genital ridges formed
Proliferation of epithelium & condensation of underlying mesenchyme
Epithelial cells of the genital ridge penetrates underlying…
Mesenchyme
Epithelium of genital ridge proliferates to form a number of irregularly- shaped cords
Primitive sex cords
Impossible to differentiate between male and femal when the genital ridge proliferates
Indifferent gonad
During the indifferent gonad stage, both males & females have two pairs of genital ducts called
Mesonephric (wolffian) ducts Paramesonephric (Mullerian) ducts
Open into urogenital sinus on either side of the sinus tubercle
Mesonephric (Wolffian) ducts
Runs lateral to mesonephric duct; crosses ventrally
Paramesonephric (Müllerian) ducts
In midline, comes in close contact with paramesonephric duct from opposite side
Paramesonephric (Müllerian) ducts
Caudal tip of combined ducts projects into posterior wall of urogenital sinus; causes small swelling
Sinus tubercle
If embryo is genetically male, primordial germ cells carry an
XY chromosome complex
Houses SRY gene
Y chromosome
Leads to the developement of testes
Testis-determining factor (TDF)
Encodes for testis-determining factor (TDF)
SRY gene
Under influence of SRY gene, Primitive sex cords continue to proliferate & penetrate deep into the medulla to form the
Testis (medullary) cords
Y chromosome -> SRY gene -> TDF -> Testis
Just a note
Primitive sex cords proliferate & penetrate deep into medulla to form
Testis (medullary) cords
Towardshilumof testis, testis cords break up into network of tiny cell strands which give rise to
Rete testis
Dense layer of fibrous connective tissue; separates testis cords from surface epithelium
Tunica albuginea
Testis cords become horseshoe-shaped & continuous with rete testis
4th month
What are the testis cords composed of?
Primitive germ cells Sertoli cells (sustentacular cells)
Supporting cells
Sertoli cells (sustentacular cells)
Where are Sertoli cells (sustentacular cells) derived from?
Testis surface epithelium
Where are Leydig cells derived from?
Mesenchyme of gonadal ridge
Lie between the testis cords
Leydig cells
Another name for leydig cells
Interstitial cells
What do leydig cells produce?
Testosterone
What week to leydig cells begin to produce testosterone?
Week 8
Allows testis able to influence sexual differentiation of genital ducts & external genitalia
Testosterone
Remain solid until puberty
Testis cord
Testis cords acquire a lumen and become
Seminiferous tubules
Seminiferous tubules join rete testis tubules which enter
Ductuli Efferentes (Efferent ductules)
Link rete testes & mesonephric (wolffian) duct
Efferent ductules
Mesonephric (wolffian) duct gives rise to
Ductus deferens (vas deferens)
Stimulates genital ducts to develope
Testosterone
What do mesonephric ducts form?
-Efferent ductules -Epididymis -Vas Deferens (ductus deferens) -Seminal Vesicle -Ejaculatory Duct EEE VS