Embryo- Development of the Genital System Flashcards
genital system develops from what mesoderm?
intermediate
lateral body folding in embryo occurs
week 4
urogenital ridge is (space)
bilateral
retroperitoneal
urogenital ridge portions
nephrogenic cord (lateral) gonadal ridge (medial)
nephrogenic cord produces
urinary structures
gonadal ridge produces
genital structures
indifferent stage of sexual development
weeks 1-6
both sets of genital ducts present
female genital ducts
paramesonephric (mullerian) duct
male genital duct
mesonephric duct (wolffian) duct
gonadal ridge formed when
week 5
how is gonadal ridge formed?
intermediate mesoderm thickens bilaterally
gonadal (cortical) cords formed when
gonadal cord cells sink into underlying mesenchyme to envelop PGCs
mesothelial cells of gonadal ridge that develop when mesothelium lining of gonadal ridge thickens
gonadal cord cells
hormones necessary for development of testes
SRY - sex determining region of Y chromosome
TDF - testes determining factor
Leydig cells develop from
gonadal ridge mesenchyme
Leydig cells produce
testosterone
Gonadal cords separate and extend into medulla of testes and envelop PGCs to form
seminiferous tubules + rete testes
sertoli cells develop from
gonadal cord cells
cord cells form primitive gonadal (cortical) cords when?
week 6
remnants of mullerian duct in male
prostatic utricle
appendix testes
mesonephric duct forms
vas deferens
superior mesonephric duct forms
epididymis
mesonephric tubule forms
efferent ductules
caudal mesonephric duct forms
seminal vesicles + ejaculatory duct
ejaculatory ducts open into
prostatic urethra
mesonephric duct derivatives
epididymis
vas deferens
ejaculatory duct
seminal vesicle
gonadal cord derivatives
seminiferous tubules
rete testes
endodermal outgrowths of urogenital sinus (male)
bulbourethral gland
prostate gland
Mullerian Inhibiting Hormone (MIH) produced by
sertoli cells (which are dev. from gonadal cord cells)
MIH causes
regression of mullerian duct (female)
when does descent of testes occur?
weeks 26-32
begins week 26 - both in scrotum by 32
gubernaculum story
ligament extends from gonad to labioscrotal swelling -> shortens and pulls down testes, vas deferens, testicular vessels thru abdominal wall -> scrotal sac
layers of spermatic cord derived from
anterior abdominal muscles + fascia
ext. spermatic fascia from
ext. oblique muscle
cremasteric fascia from
int. oblique muscle
internal spermatic fascia
transversalis fascia
patent processus vaginalis
congenital inguinal hernia
development of fluid filled cysts
hydrocele of testes/spermatic cord
failure of testes to descend
cryptorchidism
what must be absent for ovary development to occur
SRY and TDF
stromal cells of ovary develop from
mesenchyme of gonadal ridge
follicular cells of ovaries develop from
gonadal cord cells
how are ovarian follicles formed?
follicular cells formed from gonadal cord cells surround PGCs and form ovarian follicles
follicular cells are formed by
cortical cords break up, cord cells develop into flat follicular cells
follicular cells surround
oogonium
oogonia turn to primary oocytes when
months 3-7
primordial follicle made up of
primary oocyte + follicle cell capsule
low testosterone causes
mesonephric duct regression
no MIH causes
continued growth of mullerian duct (paramesonephric)
mesonephric duct remnants
epoophoron
paraophoron
Gartner’s duct cyst
mullerian duct forms what structures
superior vagina, uterus, uterine tubes
cranial ends of mullerian duct form
uterine tubes
caudal ends of mullerian ducts fuse to form
uterovaginal primordium
uterovaginal primordium forms
uterus and superior vagina
sinovaginal bulbs formed when
endodermal outgrowths formed when uterovaginal primordium comes into contact with dorsal wall of urogenital sinus
vaginal plate formation
sinovaginal bulbs separate from sinus + fuse with uterovaginal primordium
vaginal canal formation
central endodermal cells of vaginal plate degenerate
endodermal outgrowths of urogenital sinus
greater vestibular glands
urethral glands
paraurethral glands
female derivatives of gubernaculum
ovarian ligament
round ligament of uterus
peritoneal fold becomes
broad ligament
urogenital sinus becomes future
bladder
clitoris
genital tubercle
labia majora
labioscrotal swellings
labia minora
urethral folds
glans penis
genital tubercle
scrotum
labioscrotal swelling fuse at midline
penile shaft
urethral folds fold ventral + fuse
male external genitalia differentiation induced by
testosterone (leydig cells)