introduction to embryology

Question 1

primordial germ cell
what is it
derived from what
what does it give

Answer 1

first sex cell
primitive ectoderm – epiblast
gives oogonia or spermatogonia by mitosis

Question 2

timing of gametogenesis in males and females

Answer 2

in males begins at puberty

in females begins in fetal life

Question 3

primary oocyte is arrested in

Answer 3

prophase (diplotene) of meiosis 1

Question 4

when are first and second polar bodies released

Answer 4

first —24 hrs before ovulation; second at fertilization

Question 5

secondary oocyte is 
   arrested in
   gets
   waits for sperm in
   if no fertilization

Answer 5

metaphase 2
ovulated
fallopian tube
gets degenerated in 24 hrs and gets menstruated

Question 6

fetilization occurs in

Answer 6

ampulla of fallopian tube

Question 7

meiosis occurs where in males and females

results in formation of

Answer 7

seminiferous tubules in males and ovaries in females

four gametes with half no chr and half amt of genetic material

Question 8

meiosis promotes exchange of maternal and paternal dna by

Answer 8

cross over

Question 9

tetrad formation and cross over occurs in

Answer 9

pachytene stage of meiosis

Question 10

primordial germ cell arise in —– migrate to —–(–) then to ——

Answer 10

epiblast
wall of yolk sac (endoderm)
gonadal ridge

Question 11

y chr is
where is sry region
what does it code for

Answer 11

acrocentric
on short arm of y chr
testis determinig factor

Question 12

what are needed for development of indefinite embyo to male embryo

Answer 12

testosterone
mullerian inhibitory hormone
testis determinig factor

Question 13

spermatogenesis occurs in
pgc arrive at testes at wk —-and remain —-
at puberty—-

Answer 13

seminiferous tubules
wk 6….dormant till puberty
give spermatogonia

Question 14

pgc arrive in ovary at wk
all primary oocytes are formed by
get arrested in—-till —-

Answer 14

wk 6
fifth month of fetal life
prophase 1 till puberty

Question 15

what is cumulus oophorus and what does it contribute to

Answer 15

granulose cells (epithelial cells) surrounding oocyte in sec follicle stage
contribute to corona radiata

Question 16

first layer to form

Answer 16

endoderm followed by ectoderm

Question 17

gastrulation is
starts with
when

Answer 17

formation of three germ layers
fomation of primitive streak
beginning of third wk

Question 18

fate of primitive streak and its remnants

remnants of notochord

Answer 18

becomes inconspicuous
sacrococcygeal teratomas
nucleus pulposus and apical ligament of dens

Question 19

when does implantation occur
fertilization when
two cell stage when
morula has - to - blastomeres and when

Answer 19

6-11 days
12-24 hrs after ovulation
30 hrs of age
12 -16 ; 3 days of age