Flashcards in SEX DETERMINATION Deck (78)
when is sex determined?
at fertilisation - however they remain undifferentiated until 6 weeks
what is the result of presence of SRY gene?
it leads to development of testis
what is the result of non SRY gene?
it leads to ovary production
what determines the sex?
what is the Barr body?
the non-functional X in female gonads condense to form a nuclear mass - the Barr body
which part of the embryo are the genital organs derived from?
the intermediate mesoderm - they come from the genital ridge
where is SRY gene expressed?
in the genital ridge
where do the germ cells for sperm and ova come from?
the yolk sac of the hindgut
which duct system develops the male reproductive tract?
which duct system develops the female reproductive tract?
how does the male reproductive tract form?
- sertoli cells produce mullerian inhibitory factor (MIF)
- this leads to testis determining factor (TDF) - this influences the formation of male gonads
- leydig cells produce testosterone which converts the wolffian duct into the epididymis, vas deferens, ejaculatory duct and seminal vesicles
- primitive sex cords develop
what does the wolffian duct produce?
what structure forms deep in the medulla of the testis?
the cord of the testis
what structure forms at the hilum of the testis?
what is the tunica albuginea?
it is dense connective tissue under the epithelia
what is DHT (from testosterone) involved in forming?
the development of the penis, scrotum and prostate
what causes the testes to descend into the scrotum?
testosterone (usually occurs post-natally)
what does the mullerian duct produce?
upper 2/3 of vagina
what does the lower 1/3 of the vagina and external genitalia form from?
the urogenital sinus
what development occurs in females in week 7?
2nd generation cords penetrate underlying mesenchyme
what development occurs in females in month 3?
cords split into isolated clusters which surround oogonium and follicular cells
what does oestrogen form?
when is the best time to introduce sperm in the menstrual cycle for fertilisation to occur?
introduce sperm 5 days before to 1 day after ovulation
how long can sperm survive for?
how long can an egg survive for?
how is the egg transported from the ovary to the uterus?
- extruded from the ovary as digestive enzymes break the surface membrane
- carried out by antral fluid
- smooth muscle and fimbriae move the egg to the fallopian tube
- cilia in fallopian tube carry egg to the uterus
what is the viscosity of a woman's mucus dependent on?
the woman's hormone levels
why is high oestrogen an advantage to sperm in woman's body?
- glucose comes from oestrogen
- higher oestrogen means more glucose so the sperm can last longer
what are the conditions of the vagina?
high in nutrients