Development of the urogenital system Flashcards
What does the intermediate mesoderm form?
It forms the urogenital ridge which will then give rise to the nephrogenic cord
and the gonadal ridge which gives rise to the male/female genital tract
What does the medially positioned gonadal ridge give rise to?
ovary/testis (male/female genital tract)
Where does the pronephros develop from?
The neck region
Where does the mesonephros develop from?
thorax/lumbar region
Where does the metanephros develop from?
The pelvic region
Where does the kidney develop from in the mammal?
The metanephric region
What are the two sources that the metanephros develops from?
The Ureteric bud or the metanephrogenic bud
Where does the ureteric bud grow out of?
Grows out of the mesenephric duct and eventually develops into the ureter, renal pelvis and collecting ducts
What does the metanephrogenic mass form?
Outer part of the mass forms the capsule and interstitium of the kidney, the inner parts form the nephrons
What does the urorectal septum divide the cloaca into?
Dorsal, Rectum, anal canal and anal membrane
What is the trigone?
triangular region located in the dorsal wall of the bladder neck formed by longitudinal smooth muscle from the ureters
Where do the gonads develop from?
gonadal ridge which is a thickening of the intermediate mesoderm
What are the two types of cells that the gonad contains?
Supporting cells and germ cells
What do the supporting cells form?
cellular cords
What do germ cells proliferate and migrate inside of
The gonadal cords so that they can be surrounded by supporting cells
What can an indifferent gonad then become?
either an ovary or testis
What do the germ cells within the seminiferous cords become?
spermatogonia
What happens to the seminiferous cords during puberty?
They canalise to become tubules, germ cells within begin to initiate spermatogenesis
What happens to the cord cells that lack germ cells?
They become part of the rete testis
What do the supporting cells differentiate into?
either leydig cells or sertoli cells
What is the name of the cells that are in the walls of the seminiferous tubules and suppress both spermatogenesis and female duct development ?
sustentacular cells
What do the interstitial cells (located outside of the seminiferous tubules) become?
Two different populations, one of them produces androgen hormones immediately, the other delays androgen production until sexual maturity
What causes the paramesonephric ducts to regress in the seminiferous tubules?
they regress due to an inhibitory hormone produced by the sustentacular cells of the testis
What does the cranial region of the mesonephric duct become?
It undergoes elongation and coiling to become epididymis
What does the remaining region of the mesonephric duct become (not cranial)
Enlarges to become ductus deferens
What do the female germ cells differentiate into?
they differentiate into primary oocytes
What fails to develop in the absence of testosterone?
mesonephric ducts
What does the cranial part of the paramesonephric duct become?
It stays open and becomes uterine tube
What does the genital tubercle become in the male and female?
glans penis and clitoris
What does the genital swelling become in the male and female?
Scrotum and labia majora
What do the mesodermal cells next to the metanephrogenic mass grow and form?
Cell cords
What happens to the cell cords after they are formed?
They canalise and elongate to become s-shaped metanephrogenic tubules
