Lec 28 Sexual Differentiation Flashcards
What are the 3 types of sexual differentiation in order?
- genetic sex [XY or XX]
- gonadal sex [testes or ovaries]
- phenotypic sex [secondary sex characteristics, external genitalia]
Which type of internal ducts to males vs females have?
males: wolffian
females: mullerian
what do wolffian ducts turn into
- epididymis
- vas deferens
- seminal vesicles
what do mullerian ducts turn into
- uterus
- fallopian tubes
Until what time in embryo are gonads bipotential?
5 weeks
What do testes develop?
wks 6-7
when do ovaries develop?
wk 9
What determines genetic sex differentiation?
presence or absence of Y chromosome
Is sry gene located in pairing region [where x and y can cross over]?
NO!
What is the pairing region of the y chromosome?
the part of the y chromosome that can cross over with the x chromosome
What is swyer’s syndrome?
- XY individual that has no SRY gene
- testis do not form, no testosterone, no anti-mullerian hormone
- internal system forms fallopian and cervix
- gonads aren’t really testis or ovaries
- do not prove testosterone
- present at puberty with delayed sexual maturation, appear to have normal female internal/external genitalia
- sex assignment usually female
- give estrogen/progesterone
What happens if sry crosses over to X?
- get X + sry gene
- with x egg becomes XX male
- appear phenotypically male
sertoli function
- located of spermatogonia
- secrete AMH - antimullerian hormone]
What do leydig cells produce
testosterone
What do granulosa cells in ovary produce?
estradiol
What do theca cells in ovary produce?
progesterone
What 2 genes required for ovarian differentiaton?
- wnt4
- rsp01
what 3 genes required for testicular development?
- SRY
- SOX 9
- Fgf9
What is effect of testosterone on early male differentiation?
- local testosterone stimulates wolffian duct growth and differentiation to epididymis, vas deferens, seminal vesicles, ejaculatory ducts
What is effect of AMH on male differentiation?
cause atrophy of mullerian ducts
What do penis and scrotum differentiate? what hormone required?
- 9-10 wks
- dihydrotestosterone [DHT] required
What happens in absence of testosterone?
wolffian ducts regress
Where does DHT come from? why is it importnat?
- reduced from testosterone from 6a reductase
- needed for differentiation of external male genitalia
When does fetus become fully differentiated as male?
12 wks
What is androgen insensitivity syndrome?
- phenotypic female [will have breast development, minimal pubic/axillary hair]
- no menstruation [primary amenorrhea]
- blind ending vagina
- genetically XY
- sry gene works fine, testis make AMH, no uterus/fallopian tube
- androgen receptor defect so testosterone can’t make wolffian duct and no DHT so external female
What is congenital adrenal hyperplasia?
- masculinization of female external genitalia at birth
- normal uterus, fallopian tubes, ovaries
- menstruates at puberty
- genetically XX
- has mullerian ducts
- no wolffian ducts
- adrenal making too much androgen, causes masculinization of external genitalia –> fused labia, enlarged clitoris
- most common 21 hydroxylase deficiency
- not making aldosterone
for XY: no
What is mech behind too much androgen in congenital adrenal hyperplasia
- deficiency in 21 hydroxylase so get build up of side products in rxn in adrenal
- ACTH sending signal to make cortisol and usually cortisol gives negative feedback, without ability to properly make cortisol don’t have negative feedback
- have low cortisol and aldosterone
- high androgen
What hormone determines puberty? continuous or pulsing?
- increasing pulse frequency and amplitude of GnRH release turns on puberty
