| Question |
Answer |
| When are primordial germ cells in male and female generated? |
embryogenesis |
| What are the chromosomal sex determinates? |
XX and YY |
| What does expression of the gene SRY on chromosome Y result in? |
testes (male) |
| What determines gonadal sex? |
presence of testes vs ovaries |
| What is the source of hormone which determines external and internal genitalia? |
gonad |
| What is phenotypic sex? |
external and internal genitalia |
| What is necessary for maleness? |
SRY |
| Is SRY sufficent for maleness? |
NO |
| What in addition to SRY is necessary to have a phenotypic male? |
genes on X chromosome that encode the testosterone receptor |
| When is male phenotype induced? |
after 8 weeks of gestation |
| Sexual differentiation |
the process by which specific gene products result in a gonad whose products make possible a male or female phenotype |
| female ducts |
Mullerian ducts |
| male ducts |
Wolferian ducts |
| What do Sertoli cells secrete? |
Mullerian inhibitory hormone (MIF) |
| What does MIF cause? |
regression of mullerian ducts in male |
| sexual identity |
refers to whether indviduals consider themselves male or female |
| sexual preference |
refers to whether individual is attracted to the same sex or the opposite sex |
| sexual functioning |
refers to whether an individual has testes, ovaries, or gonads with both features |
| hermaphroditism |
gonads with both features - retain Wolferian and Mullerian ducts |
| What responds to levels of circulating steroid hormones? |
hypothalamus |
| What does GnRH regulate? |
FSH and LH |
| What do FSH and LH do? |
regulate the development and function of the gonads in male and female |
| What is GnRH secretion like in male? |
continuous and pulsatile |
| What is GnRH secretion like in female? |
cyclic (monthly pattern) |
| How sensitive is the hypothalamus in development? |
super-sensitive |
| How sensitive is the hypothalamus in adult? |
feedback |
| What does inhibin do? |
inhibits FSH |
| Does inhibin occur in males or females? |
both |
| what causes negative feedback of inhibin? |
local secretion of testosterone |
| What is kespeptin? |
clock that has to be turned on, allows hypothalamus to gain adult rhythms - absence of these genes products prevents puberty |
| Where are sperm made? |
testes |
| Where do sperm go from the testes? |
epididymis |
| Where do sperm go from the epididymis? |
vas deferens |
| How much sperm is in typical ejaculate? |
> 100 x 10⁶ sperm per 5 ml |
| What does the blood-testes barrier do? |
prevents immune system from accessing developing sperm - protects stem cell population |
| What do the leydig cells produce? |
testosterone and DHT |
| What do the sertoli cells produce? |
various hormones |
| What coordinates the production of sperm? |
hypothalamus |
| What is the length of the seminiferous tubules? |
length of 3 football fields |
| What is the length of epididymis? |
6 feet |
| How many days does it take to go from a spermatogonium to a spermatozoon in the lumen? |
64 days |
| Can sperm swim when they are released from seminiferous tubules? |
no - they are immobile |
| How long does it take for a sperm to be mobile? |
90 days |
| What does the epididymis do to the sperm? |
further differentiate, help them become mobile |
| When do sperm become good swimmers? |
in the ova duct - they learn how to swim then - they bury their heads in the ova duct epithelium, searching for an egg |
| What is the hormone control by sertoli cells? |
testes-blood barrier, androgen binding protein, inhibin, convert testosterone to estradiol |
| What is 5 α reductase? |
critical for making DHT |
| What is DHT? |
dihydrotestosterone |
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