atresia and ovulation Flashcards
what is atresia
inseverable degradation follicle and oocyte before it can ovulate
what is the follicle and oocyte deprived of before becoming antral
- important signaling molecules
- various growth factors
what does every normal ovary contain most of
atretic follicles
when does the greatest wastage of germ cells occur
before birth
when do the number of oocytes peak within the fetal ovary
midway through gestation
estradiol is positive feedback so what does it cause
GnRH surge
what happens after a GnRH surge
LH surge
what does the LH surge trigger
triggers ovulation
why is there only an LH surge
cause inhibin reduces or blocks the production of FSH
two types of ovulators
- induced
- spontaneous
steps to ovulation
GnRH surge
LH surge
ovulation occurs
example of induced ovulator
cats
another name for induced ovulator
reflex ovulators
what causes ovulation in induced ovulator
vagina or cervix stimulation
what typically has a long copulation or high frequency copopulation
induced
example of spontaneous ovulator
cattle
sheep
pigs
horses
dogs
chickens
how does ovulation occur in spontaneous ovulators
in repsonse to hormones/cycle
no stimulation required for ovulation
spontaneous ovulators
what four things does LH surge do
- causes intra-follicular PGE2 production
- changes intra-follicular steroid production
- causes intra-follicular PGF2alpha production
- gap junction breakdown
what happens when intra-follicular PGE2 production occurs
- increases blood flow to follicle (hyperemia)
when there is an increase of blood flow to follicle, what can also happen
increases edema
changes in intra-follicular steroid production cause
switch in estradiol to progesterone
what does progesterone stimulate
collagnease activity in theca cell
collagenase breaks down what
collagen
