Follicular Cycle Flashcards
dominant hormone in luteal cycle
progesterone
luteinization is
the transformation of folliclear cells (theca interna and granulosa cells) into luteal cells after ovulation
luteolysis is
the regression of the corpus luteum
large luteal cells (llc)
originate from granulosa cells, secrete progesterone and oxytocin
small luteal cells (slc)
originate from the cells of theca interna, secrete progesterone
define folliculogenesis
developmental process where an activated primordial follicle develops to a preovulatory size through the growth and differentation of the oocyte and it’s surrounding granulosa cells
ovarian follicles are classifed based on
- the number of granulosa cells surrounding the oocyte
- the morphology of the granulosa cells
- their dieameter
- the presence or absence of the antrum
the primordial follicle consists of
an oocyte surrounded by a single layer of SQUAMOUS follicle cells
the primary follicle consits of
a single layer of CUBOIDAL follicle cells surrounding the oocyte
the tertiary follicle consits of
- a fluid filled antrum
- granulosa cells, basal lamina, theca interna and theca externa cells
the graafian follicle or preovulatory follicle conists of
primary to secondary stage oocytes
during the gonadotropin-independent phase
the follicle grows through primordial, primary, and secondary stages, INDEPENDENT of FSH and LH
Gonadotropin-responsive phase
- follicle transiton from the preantral stage to the early antral stage
- primarily controlled by intraovarian regulators but can be stimulated by FSH
Gonadotropin-dependent phase
- follicle growth and maturation beyond the early angral stage
- includes: follicle recruitment, selection, and ovulation, dependent on FSH and LH
recruitment
process where the follicle departs from the pool to initiate growth
selection
process where the mature follicle chohort is reduced in number
dominance
status of the follicle destined to ovulate, and it’s role in regulating the ovulatory quota
atresia
the degeneration and reabsorption of ovarian follicles
fsh is responsible for ___ (in follicules)
- maturing them (transition from secondary to ovulatory)
- generally, follicule recruitment and inital growth
FSH high/low
- highly expressed in granulosa cells of small antral follicles (mid estrus)
- strongly supressed when the follicle is secreted (ovulation)
During follicule secretion
- FSHR is supressed
- LSHR is induced
selection of a dominant follicle for selection and maturation invovles
- becoming dependent on LH
- greater capacity for estradiol production
- activation of IGF system
- antiapoptotic follicular microenviornment
ovarian aging is characterized by
gradual decline in quantity and quality of oocyte or follicular pool (degenerative process called atresia)
ovarian aging in cow
after the fourth year of life, the number of ovaries decline until about 3,000 are left in cows 15-20 yrs old
high/low hormones during proestrus
decreasing progesterone
increasing estradiol, LH, and FSH
FSH drops right before estrus
high/low hormones during estrus
peak estradiol, LH, and FSH
low progesterone
two cell gonadotropin theory
- collaboration between theca interna and granulosa cells to make estrogen
1) LH surge
2) theca interna cells respond by: converting chloresterol to pregnolone (P5) and pregnenolone to androgens
4) P450 (in granulosa cells) converts antrogens to estrogen
androgens diffuse into granulosa cells and express
FSH receptors and P450
P450 transforms
cholesterol into pregnenolone
functionof P450
- transforms chloesterol into pregnenolone
- androgens to estrogens
functions of estradiol
- lordosis, phonation, increased physical activity
- increased blood flow, edema of tissues, mucus secretion, lukecytes, smooth muscle motility, growth of uterine glands
theca interna cells respond to
LH
in theca interna cells…
chloresterol –> pregnenolone –> testosterone
granulosa cells respond to
P450
in granulosa cells…
androgens are converted to estrogen
granulosa cells secrete ____which activates ____
FSH which activates P450
