Lecture 33: Genital System Pt 1 Flashcards
what directs overall gonadal development
genotype which directs external genitalia development
what are the two phases of development of the reproductive system
- embryonic development of sex organs
2. secondary sexual development (puberty)
what develops during embryonic development of sex organs (3 things)
- Gonads (testes and ovaries)
- Genital ducts
- Accessory glands
from what layer do the organs of the reproductive system predominantly develop from
intermediate mesoderm
what DOESNT develop from the intermediate mesoderm in the reproductive system
the primordial germ cells (precursors of spermatogonia and oogonia) are from the yolk sac which is endodermally derived
what happens during week 5-7 of gonadal development
migration of germ cells from yolk sac (forms genital ridge) and the thickening on the medial side of the mesonephros
NOTE: the gonads of men and women look exactly the same at this stage!! (INDIFFERENT)
when do germ cells start migrating and where do they migrate
start migrating in week four along dorsal mesentery
when do the primordial germ cells get incorporated into the primary sex cords
week 6
how is the gonadal ridge formed
proliferating epithelium and mesenchyme form half moons known as the gonadal ridge
what is the gonad formed from
external cortex and internal medulla
what does development of a male phenotype require
the short arm of a Y chromosome (contains SRY gene which produces Testis Determining Factor) which is what directs the development of the testes
what does development of a physiologically typical female require
two X chromosomes
absence of y chromosome leads to
ovaries
what doe the primary sex cords become in men
seminiferous cords, tubules and rete testes
what does primary female sexual differentiation NOT depend on
female hormones (more important is the lack of testosterone)
testes secrete
testosterone which leads to male differentiation
how does the type of gonad come to differ
differentiation within genital ducts and external genitalia
how do rete testes develop
from branching and anastemoses of sex cords
what is the tunica albuginea
thick capsuel separating sex cords from surface epithelium; diagnostic of testicular development in a fetus.
what is the mesorchium
what seperates the enlarging testes from the degenerating mesonephros (it is a mesentery)
what gives rise to the cells of leydig
seminiferous tubules become seperated by a mesenchyme that gives rise to these interstitial cells
when do interstitial cells of leydig arise
week 8
what do interstitial cells of leydig secrete (when do they start)
testosterone and androstenedione – week 8
*this is masculine differentiation of mesonephric ducts and external genitalia – from mesonephric ducts
where are sertoli cells and what do they secrete
secrete antimullerian hormone (AMH) and they are in the testes
what is the function of AMH
supresses development of mullerian (paramesonephric) ducts through puberty
what kind of cells are in the seminiferous tubules
2 types
1) sertoli
2) spermatogonia (primordial sperm cells derived from primordial germ cells)
decribe the seminiferous tubules until puberty
solid
describe the formation of the ductus epididymis
rete testis become continuous with 12-20 efferent ductules which are connected to the mesonephric duct which becomes the ductus epididymis
what is required for the development of ovaries
x chromosome and autosome
what happens to the primary sex cords in women
they degenerate along with the rete ovarii
what gives rise to the cortical cords in women
the secondary sex cords – cortical cords increase in size and primordial germ cells get incoporated into them
what do primordial follicles consist of
oogonium and follicular follicles derived from sex cord
when are all oogonia formed by
birth (about 2 million)
at the indifferent stage (5-6 weeks) what kind of ducts are present`
mesonephric (wollfian) ducts which drained urine from mesonephric kidneys
paramesonephric (mullerian) ducts
what do mesonephric ducts become
proximal: convolutes to form epididymis
lateral: seminal vesicles
remainder: ductus deferens and ejaculatory duct
where is the ejaculatory duct
the part of the mesonephric duct between seminal vesicle and urethra
what is the function of the seminal vesicles
produces fluid that nourishes sperm and also makes vagina more alkaline for motility
how does the prostate develop
endodermal outgrowths of prostatic urethra and surrounding mesenchyme
what is the function of the prostate
produces fluid for semen – sperm transport (in the first part of ejaculate)
what are the bulbourethral glands formed from
outgrowths of spongy urethra
what do the bulbourethral glands do
secretions contribute to semen
what causes the mesopnephric ducts to regress in women
no testosterone
what does no MIS cause in women
paramesonephric ducts develop
what forms the paramesonephric ducts
WOMEN!!! invaginations on lateral mesonephrons approach and fuse, creating ducts
where do the paramesonephric ducts pass
caudally into the pelvic region. they develop lateral to gonads and mesonephric ducts
what is the uterovaginal primordium
meeting of paramesonephric ducts in the pelvic region (y shaped)
what does the paramesonephric duct become
the fallopian tubes (unfused part before the uterovaginal primordium)
what does the uterovaginal primordium become
the vagina and uterus
what is the mulleriuan (sinus) tubercule
projection of uterovaginal primordium into urogenital sinus
what causes the formation of the broad ligament
the fusion of the paramesonephric ducts brings together 2 peritoneal folds that form the broad ligament
what causes the formation of the vaginal plate
uterovaginal primordium meets urogenital sinus forms sinus tubercule which induces formation of paired endodermal outgrowths (sinovaginal bulbs). these bulbs fuse to form the vaginal plate
how does the vaginal plate become the vagina
central cells break down and you get a lumen.
what separates the lumen from the cavity of the urogenital sinus
the hymen
what forms Skene’s glands
buds from urethra form urethral and skenes (paraurethral)
what forms bartholin’s glands
buds from urogenital sinus
homologous auxillary genital glands from urethra
women: urethral and paraurethral glands
men: prostrate
homologous auxillary genital glands from urogenital sinus
women: greater vestibular glands of bartholin
men: bulbourethral glands
