repro Flashcards
what is nondisjunction?
when chromos do not separate properly after division
what are the various types of abnormal sex distribution syndromes?
Klinefelters, XXY; Turner's syndrome, X Y is non viable XYY... XXX-->no distinct phenotypes
when do repro structures differentiate?
seventh week of development –prior to this time they are considered bipotential
Male or female development depends on the presence or absence of sex determining region of the Y chromosome (SRY gene)
ya
how to the bipotential gonads form female gonads?
gonadal cortex forms ovary while the medulla regresses; wollfian duct also regress because of lack of testosterone; mullerian duct becomes fall tube, uterus, cervix, and upper half of vag
how to the bipotential gonads form male gonads?
gonadal cortex regresses; medulla forms testis; wolffian duct forms epididymis, vas def, and seminal vesicles (presence of testosterone); mullerian duct regresses due to AMH
how does the SRY gene dictate sex?
SRY gene produces TDF (testis determining factor)–>creates SOX9, WT1, SF1–.guides development of gonadal medulla into a testis; testes then produce:
- Anti-Mullerian hormone (sertoli cells): causes mullerian ducts to regress
- Testosterone (leydig cells): converts Wolffian ducts into male accessory structures (epididymis, vas deferens, and seminal vesicles)
- Dihydrotestosterone (leydig cells): differentiation of external genitalia–development of prostate
what causes formation of external genetalia?
External genitalia development driven by presence or absence of androgens (DHT)
describe female gametogenesis
during embryogenesis, oogonium undergo mitosis then meosis I–generate primary oocytes; at puberty, primary oocyte splits into secondary oocyte and polar body; secondary oocyte released as egg during ovulation, then will complete meiosis II when fertilized
describe GnRH release
- Released from hypothalamus in pulsa)le fashion every 1-3 hours in both sexes
- -females also have a surge corresponding with ovula)on
- children with a GnRH deficiency will not mature sexually without gonadtrophin s)mula)on of the gonads
- synthe)c GnRH must be delivered in a pulsa)le manner
- constant delivery of GnRH leads to down regula)on of receptors in the pituitary gonadotropes
- high GnRH treatment for certain breast or prostate cancer
what is the erectile tissue of the penis?
- Corpus spongiosum
- Corpora cavernosa
what is involved in prostate development?
DHT
how can prostate cancer be treated?
-administra)on of 5a-reductase inhibitor (finasteride) blocks DHT production, shrinks hypertrophied prostate
describe the seminif tub
- -site of sperm production
- -Developing spermatocytes stack in columns from outer edge to lumen with sertoli cells between each column
- –found in inters))al )ssue produce testosterone during development then again ader puberty
Basal lamina of seminif tubule keep out large par)cles but allows testosterone to enter
improtant for developing sperm
describe sertoli cells
- cntain tight junction with adjacent sertoli cells forming a blood- tes)s barrier between tubule lumen and inters))al space
- regulate sperm development -“sustentacular cells” provide sustenance or nourishment
- Produce a variety of substances: hormones (ac)vin & inhibin); growth factors; enzymes; and androgen binding protein (ABP) which binds to testosterone to keep it in the tubule lumen
describe how GnRH neurons activate to release hormones
GnRH-containing neurons are cyclically activated to fire APs–>release trophic hormones (GnRH) which are released into the first capillary bed; they are then carried to endocrine cells with GnRH receptors in anterior pit gland where a second cap bed lies; they acts on endocrine cells to release their peptide hormones–>LH and FSH–>enters blood stream and goes to gonads
what is the blood testes barrier
a lining of sertoli cells which provide a barrier between the blood and seminif tubs; improtant, because gametogenesis is very sensitive–xenos in blood could destroy developing sperm
where do spermatids compete transformation, and what occurs?
–remain embedded in apical membrane of sertoli cells–>lose most cytoplasm, form a flagellum; chromatin condenses, acrosome forms and caps the nucleus; a mid piece forms which is needed for energy (contains mito);