Reproductive System Development Flashcards
How long are gonads and genitalia morphologically indistinguishable
Up to week 7 of development
Urogenital ridges
. Paired columns of intermediate mesoderm running the length of the dorsal body wall
Gonadal ridge
. Med. portion
. Coelomic epithelium proliferates and gives rise to gonads
Nephrogenic ridge
. Lat. portion
. Gives rise to primitive kidney tubules and 2 sets of ducts that contribute to urinary and reproductive duct systems (mesonephric and paramesonepric. Mullarian ducts)
What occurs w/ gonad differentiation in weeks 4-6
. Primordial germ cells (future gametes) migrate from the yolk sac along dorsal mesentery and into gonadal ridge
What occurs in week 5 of gonad differentiation?
. Coelomic epithelium of gonadal ridge proliferates to form primary sex cords
. Testes or ovaries then develop based on presence of Y-chromosome in terms cells or not
SRY gene
. On Y-chromosome
. Encodes for production of protein testis-determining factor
Testis-determining factor
. If expressed, gonads develop into testes
. If not expressed, gonads develop into ovaries
Streak gonads
. Gonads that fail to develop into testes or ovaries
What occurs in weeks 6-7 of testis development?
. Primitive cords proliferate w/ TDF into testis (medullary) cords
. Testis cords from rete testis and seminiferous tubules
. Rete testis join efferent ductules from mesonephric tubules
. Spermatogonia take up residence in basal compartment of seminiferous tubules
. Somatic cells derived from mesoderm of gonadal ridge form Sertoli cells
Are testis primarily medulla or cortex?
. Medulla bc it contains seminiferous tubules and spermatogonia
. Cortex only contains tunica albuginea
What occurs in week 8 of testis develop?
Sertoli cells produce mullerian-inhibiting substance and testosterone
. suppresses development of paramesonephric ducts
. induces further development of non-ureter portions of mesonephric ducts and male external genitalia
.
Male Gubernaculum
. Mesenchymal condensation extends from caudal pole of each testis
. Distal end is anchored on body wall in inguinal region
. Elongation of torso causes testes to descend toward inguinal region
Where are testis located in week 28?
Descended retroperitoneal Lu from post. Abdominal wall to deep inguinal rings
.
Where is the testis location btw weeks 28 and 40?
. Descends through inguinal canals into scrotum
Cryptorchidism
. Testes fail to descend into scrota by 12th month postnatal
. Corrected surgically
. Failure to descend results in impairment of germ cell maturation
. Abdominal testes 40 times more likely to develop cancer than normal ones
Development of ovaries in weeks 4-7
. Primary sex cords initially proliferate and then degenerate w/o TDF
. Continued proliferation of gonadal ridge surface epithelium produces 2nd generation of cords (cortical cords) that are clustered in cortex fo ovary
. Oogonia invade cortical cords
. Cell of cortical cords give rise to follicular cells forming primordial follicles
Are ovaries cortex or medulla heavy?
. Cortex bc it contains majority of oogonia and ovarian follicles
. Medulla only has CT and blood vessels