021615 embryology

Question 1

sex determination occurs at

Answer 1

fertilization

Question 2

sex differentiation occurs at

Answer 2

embryonic and into fetal period

influenced by genetic, epigenetic factors

Question 3

Mullerian inhibiting hormone

Answer 3

promotes regression of paramesonephric (mullerian) ducts

Question 4

where does indifferent gonad form

Answer 4

within ventromedial aspect of nephrogenic cord

Question 5

where do primordial germ cells come from

Answer 5

yolk sac (extragonadal)
then migrate to gonad

Question 6

when do mesonephric and paramesonephric ducts develop?

Answer 6

5th wk

Question 7

urogenital sinus is

Answer 7

developing bladder

Question 8

the paramesonephric duct contacts the

Answer 8

UG sinus

Question 9

labioscrotal swellings

Answer 9

lateral to urethral (urogenital) folds

Question 10

during wks 4-7, what happens?

Answer 10

sexually dtermined but sexually undifferentiated embryo has formed (pair of undifferentiated gonads, two sets of ducts, elevations and folds around opening of UG sinus)

Question 11

differentiation of what occurs first?

Answer 11

gonad (wk 6-7)

Question 12

what causes gonad development into an ovary?

Answer 12

absence of SRY gene expression

Question 13

what causes growth and differentiation of mesonephric ducts?

Answer 13

testosterone

Question 14

derivates of mesoneprhic duct

Answer 14

duct of epidydymis
vas deferens
ejaculatory duct
seminal vesicle

Question 15

what interacts to form vagina?

Answer 15

paramesonephric ducts and pelvic part of UG sinus

Question 16

UG sinus in male in the pelvic portion becomes

Answer 16

distal prostatic and membranous urethra

Question 17

phallic portion of UG sinus in male becomes

Answer 17

penile urethra

Question 18

labioscrotal folds do what in male?

Answer 18

fuse venturally to form scrotum

Question 19

how does external genitalia deveop in female direction?

Answer 19

absence of androgens

Question 20

what directs gonads to form testes?

Answer 20

SRY gene