reproduction 4 - sexual determination and differentiation Flashcards
what is the jost paradigm
that the types of sex chromosomes determines sex, which determines gonads, which detemines the genital/phenotypic sex
when is chromosomal sex determined
at the exact moment of fertilization
how is gonadal sex determined
chromosomal sex
what causes the differentiation of bipotential gonads to become testes
SRY genes on Y chromosome
what does bipotential gonad mean
the structure can go either wat
what disorder is XXY
klinefelters syndrome
what happens in XXY to spermatogenesis
it is imparited
what causes the differentiation of bipotential gonads to become ovaries
the absense of the Y chromosome
what disorder is XO
turners syndrome
what are streak ovaries
much smaller ovaries with follicles embedded with connective tissue
what does MIH do
causes regression of the mullerian duct, thereby regression of female internal genetalia
do males have MIH
yes
where do males secrete MIH
the testes secrete it from sertoli cells
do females have MIH
no
where is testosterone secreted
leydig cells
what does testosterone cause the development of
male internal genetalia (seminal vesicle, testes, vas deferens, epididymis, and ejaculatory duct)
where does DHT come from
T is converted into DHT
what does DHT cause the development of
masculinazation of male penis+prostate gland + scrotal sac
which hormones causes the masculinazation of male external genetalia
DHT
which hormones causes the development of male internal genetalia
testosterone
what causes the development of the wolffian duct in females
absense of testosterone
what causes the absence of masculinization of external genetelia in females
absense of DHT
what causes the mullarian duct to grow into female internal genitalia
absense of MIH
which sex has their differentiation happening by “default”
female
do men have wolfian duct
yes
do men have mullerian duct
no
do women have mullerian duct
yes
do women have wolfian duct
no
what does the mullarian duct become
uterus, oviducts, etc
what does the wolffian duct become
epididymis, vas deferns, seminal vesicles, ejaculatory duct
when do the 3 peaks of testosterone happen
fetal (2nd trimester)
neonatal (before 1y/o)
puberty and declines till death
what is genotype and phenotype of congenital adrenal hypoplasia
XX, ovaries, looks male
what causes congenital adrenal hypoplasia
decreased cortisol ism ade b/c mutation –> HPA makes more ACTH (no -ve feedback from cortisol) –> cholesterol makes andreogens instead of cortisol –> causes masculinization of external genetalia
are poeple with congenital adrenal hypoplasia fertile
nope
what is the genotype and phenotype of androgen insensitivity syndrome
XY, testes, outwardly looking female
what causes androgen insensitivity syndrome
yes they have MIH so no female internal, but the cells on the Wolffian duct do not respond to T so no internal male structures
also the cells dont repond to DHT so by default they have external female structures
are people with androgen insensitivity syndrome fertile
no
what causes complete androgen insensitivity syndrome
mutation on androgen receptor
what triggers the onset of puberty
increased GnRH which causes increased LH and FSH
what is the hypothalamic - pituitary - gonadal axis like in young prepubertal children
dormant, very sensitive to negative feedback, low levels of GnRH, LH, FSH and sex steroids
what causes the activation of the hypothalamic - pituitary - gonadal axis
kisspeptin
what does kisspeptin do
postively activates the hypothalamus to released GnRH in pulses, then the ant. pit releases more LH and FSH to the gonads to make sex steroids
why do chubby girls get puberty earlier
leptin causes the release of kisspeptin
why do very athletic girls get puberty earlier
no fat so slower/ delayed release of kisspeptin
what is climacteric
the phase before menopause where periods are becoming less frequent and regular
what is menopause and what causes it
no more period because no more follicles
what is andropause
less testosterone and spem production, linked to depression
when do women reach perimenopause (how many follicles left)
1000
what happens to responsiveness to gonadotropins in menopause and what does this cause
decreased responsiveness which causes decreased estrogen and inhibit release from granulosa cells
what happens to FSH and LH in menopause and why
decrease E inhibin and P removes negative feedback on FSH(!) and LH, so they increase
what happens to FSH:LH ratio in menopause
increase
less -ve feeback holding back both, FSH most affected
what are some problems that may arise due to low estrogen
heart problems (E keeps heart healthy) and osteoperosis
