development of the urogenital system Flashcards
how does the tyolk sac anf allantoic sac form
- yolk sac forms as embryo rolls up (links to midgut and becomes choriovitelline placenta)
- allantoic sac forms as an outgrowth of the hidgut (the root with the gut becomes divided by the urorectal septum to create the hindgut and the bladder) (also becomes the chorioallantoic placenta)
what are the 3 divisions of the mesoderm and what structures arise from each
paraxial meoderm
- dermis
- axial and limb muscles
- axial skeleton
intermediate mesoderm
- nephros
- urinary ducts
- adrenal cortex
- sex cords of the gonads
lateral plate mesoderm
- tissues
- appendicular skeleton
- etc
what are the 3 sections of the nephros
- pronephros
- mesonephros
- metanephros
order is from cranial to caudal (mneumonic: PqrST)
the 3 bilaterally symmetrical sections of the nephros are connected to which cavity
coelomic cavity
the mesonephros becomes
gonads
the mesonephric duct and segmental tubules become
part of the gonads and the adrenal cortex
the metaephros becomes
definitive kidneys
the metanephric duct becomes
ureters, pelvis and collecting ducts
where does renal tissue blood supply originate
- branches of the dorsal aorta
- segmentally paired for pro and mesonephros
- paired for metanephros
- stimulates formation of nephric tubules
where do the nephric tubules originate
- segmental with pro and mesonephros
- intermediate mesoderm projects into coelomic cavity at the thoracic/lumbar region to form the bilateral urogenital ridges
where do the urinary ducts originate
- form within mesoderm
- drain nephric tubules as the paired pronephric/mesonephric ducts
compare the mesonephros and the metanephros
mesonephros
- remains as functional kidney and gonads in fish and amphibians
- regresses in mammals, reptiles and birds to produce the gonads and adrenal cortex
- segmental blood supply
- mesonephric ducts become ductus deferentes in mammals, reptiles and birds
metanephros
- becomes dominant as embryo grows
- distinct from the mesonephros
- takes over from the mesonephros
- kidneys in mammals, reptiles and birds
- separate metanephric (ureteric) duct
in the mammalian embyro, what happens to the pronephros, mesonephros and metanephros
- pronephros atrophies
- mesonephros develops then regresses as ambyro grows (part that doesnt regress = gonads)
- metanephros develops into paired outgrowths of mesonephric ducts (ureteric buds) to meet local mesodermal masses called metanephros to become kidneys
discuss how the paramesonephric ducts form in both sexes
- extra pair of ducts form, initially from grooves in abdominal wall lateral to nephros
- grooves sink into the mesoderm of the abdominal wall to become paramesonephric ducts
- the PMN ducts start to form in males but will regress (remain in females)
- PNM ducts elongate cranially and caudally
- the PMN ducts fuse or not according to the species to become Left and Right uterine horns
- remain open at the cranial ends (ampullae of oviducts)
- caudal ends induce and bud to form the endoderm of the cloaca and forms vagina and cervix
- mesonephric ducts within gonads regress
- ovaries migrate caudally to a post renal position
- the fused region og the PMN ducts becomes the body of the uterus
- the fusion of the body with the cloaca becomes the cervix and vagina
what happens to the mesonephric ducts and tubules in males
- mesonephric tubules forms the efferent ducts
- mesonephric duct forms the epididymis and ductus deferens
how do the testicles develop
how do the ovaries develop
what is the fate of the mesonephros as gonads
what is the fate of the mesonephros as adrenal glands
list some urogenital developmental defects
