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Flashcards in SEX DETERMINATION Deck (78)
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1

when is sex determined?

at fertilisation - however they remain undifferentiated until 6 weeks

2

what is the result of presence of SRY gene?

it leads to development of testis

3

what is the result of non SRY gene?

it leads to ovary production

4

what determines the sex?

the spermatozoa

5

what is the Barr body?

the non-functional X in female gonads condense to form a nuclear mass - the Barr body

6

which part of the embryo are the genital organs derived from?

the intermediate mesoderm - they come from the genital ridge

7

where is SRY gene expressed?

in the genital ridge

8

where do the germ cells for sperm and ova come from?

the yolk sac of the hindgut

9

which duct system develops the male reproductive tract?

wolffian duct

10

which duct system develops the female reproductive tract?

mullerian tract

11

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

12

what does the wolffian duct produce?

epididymis
vas deferens
ejaculatory duct
seminal vesicles

13

what structure forms deep in the medulla of the testis?

the cord of the testis

14

what structure forms at the hilum of the testis?

rete testis

15

what is the tunica albuginea?

it is dense connective tissue under the epithelia

16

what is DHT (from testosterone) involved in forming?

the development of the penis, scrotum and prostate

17

what causes the testes to descend into the scrotum?

testosterone (usually occurs post-natally)

18

what does the mullerian duct produce?

fallopian tubes
uterus
upper 2/3 of vagina

19

what does the lower 1/3 of the vagina and external genitalia form from?

the urogenital sinus

20

what development occurs in females in week 7?

2nd generation cords penetrate underlying mesenchyme

21

what development occurs in females in month 3?

cords split into isolated clusters which surround oogonium and follicular cells

22

what does oestrogen form?

uterine tubes
uterus
cervix
vagina
labia majora
labia minora
clitoris

23

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

24

how long can sperm survive for?

4-6 days

25

how long can an egg survive for?

1-2 days

26

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

27

what is the viscosity of a woman's mucus dependent on?

the woman's hormone levels

28

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

29

what are the conditions of the vagina?

highly acidic
high in nutrients

30

what are the adaptations that allow sperm motility?

fluid pressure of ejaculate helps transport sperm
sperm can move themselves using their tail (flagellum)