Lesson 69 functions of female reproductive system

the surge center is activated by high estradiol levels and trigger a GnRH surge for ovulation

How does hypothalmic center regulate GnRH secretion during estrus cycle

hypothalamus-pituitary-ovarian axis

ovulation and luteolysis

events of estrus cycle

corpus luteum

what the ovulatory follicle becomes after ovulation and starts producing progesterone

proestrus and estrus

what stages are in the follicular phase

metestrus and diestrus

what phases are in the luteal

Proestrus

very short phase characterized by active follicular growth and estrogen production. Nonexistent in queens since they are induces ovulators

etsrus

“heat” female shows sexual receptivity to males. Estrogen is very high and induces estrus. Ovulation occurs at the end of this stage whereas cows it occurs after

metestrus

transitional phase b/w diestrus and estrus where corpus luteum is developing. Only present in mares, ruminants, and sow-they ovulate in this stage

Diestrus

longest stage in the cycle characterized by mature CL and high levels of progesterone. Luteolysis occurs at the end of this stage if female does not get pregnant

Anestrus

stage where female does not exhibit estrus cycle. ovaries are inactive. Results from insufficient GnRH pulses(low FSH and LH)=low level estrogen and progesterone.

cow estrus cycle

about 21 days. has metestrus stage. Polyestrus

estrus stage last 18 hours

Cow

Dog vs cow which one ovulates a mature oocyte

Dog

Dog vs cow. which one ovulate an immature oocyte

dog-end of proestrus. cow- estrus

When does estrogen peak in both dog and cow

dog-beggining of estrus. cow- end of estrus

when does LH peak in both dog and cow

dog- increasing at the begining of estrus. cow- low during estrus

What does the progesterone lv look like in estrus in dogs and cows

Bitch’s estrus cycle

6-7 month avg. Monestrus. estrus lasts 9 days. signs of bloody discharge

ovulation occurs in estrus stage

follicular phase

begins after luteolysis and ends with ovulation. peak estrogen secretion, sexual receptivity. high estrogen causes positive feedback on surge center for release of GnRH.

Luteal phase

begins after ovulation and formation of CL, ends with luteolysis. has high progesterone lvs. no sexual receptivity. high progesterone cause negative feedback on GnRH= prevents LH surge

oxytocin and prostaglandine (PG2F_a)

2 hormones produced in the luteal phase

oxytocin

hormone release by aged CL at the end of diestrus that induces production of pgf2a

prostaglandin (PGF2a)

hormone that induces luteolysis in the CL

follicular waves

ovarian antral follicules grows in waves called ______

follicular dynamic

sequence of follicular waves during estrus cycle is called ______

FSH

Adding what hormone can stimulate more follicles growing during the follicular waves

4 stages of follicular dynamic

recruitment, selection, dominance, atresia

recruitment

stage in follicular dynamic where group of follicles grow and secrete estradiol

high FSH, low LH, low inhibin

levels of FSH, LH, and inhibin during recruitment phase

Selection

stage in follicular dynamic where the follicles that have not undergone atresia keep growing and become selected

Low FSH, moderate LH, low inhibin

levels of FSH, LH, and inhibin during selection phase

Dominance

stage in follicular dynamic where one or more preovulatory follicles are exerting an inhibitory affect on the other follicles trying to grow

low FSH, high LH, high inhibin

levels of FSH, LH, and inhibin during dominance phase

function of inhibin

suppresses FSH release from anterior pituitary gland which prevents more follicles from growing

function of LH

stimulates estrogen production in follicular phase

triggers ovulation via surge

supports LH and progesterone secretion during Luteal phase

LH surge

high estrogen reaches its peak in proestrus and causes ____

atresia

follicular degenerationn during any of the stages of follicular dynamics

luteolysis

occurs at the end of diestrus and beginning of proestrus

Progesterone

what hormone is decreasing from CL during luteolysis

hormone flow during ovulation

decrease P4 from CL→ increased GnRH from negative feedback loop with P4 removed→ increased FSH and LH in response to GnRH→ follicle develops

follicle releases E2 and then dominanting ones secrete inhibin as well to suppress FSH→e2 causes massive release from positive feedback GnRH→ LH surge

tonic center

what controls basal level GnRH during longer periods of estrous cycle

surge center

what causes high amplitude, massive releases of GnRH that occur at threshold level E2

folliculogenesis

process where follicles grow and develop

granulosa cell

projects cytoplasmic extension through zone pellucida and into oocyte allowing nutrient delivery

primordial follicles

inactive and smallest follicle with layer of flat granulosa cell

primary follicles

single layer of cuboidal granulosa cells

secondary follicles

multiple layers cuboidal granulosa cells

tertiary (antral) follicle

develops antral cavity

Mature (dominant) follicle

ready for ovulation

FSH and LH

GnRH causes the release of what hormone form anterior pituitary gland

antral follicles

what forms in response to basal levels FSH and LH

independent

primary to secondary follicle are gonadotropin ____________

Dependent

tertiary → mature follicles are gonadotropin ______

oogenesis

process of development and maturation oocyte within follicles

ooginia

stem of female cells. diploid that multiple via mitosis during fetal life

primary oocyte

starts meiosis 1 and is arrested in prophase I until puberty

basically primordial, primary and secondary follicles

secondary oocyte

after meiosis is resumed oocyte arrested again in metaphase II until fertilization (tertiary/antral follicle)

zona pellucida

glycoproteins that are synthesized and surrounds the oocyte

granulosa cells and gap junction

what cell mediates oocyte growth and what type of junction connects them

How oocytes division/ meiosis is resumed

normally cAMP inhibits meiosis but LH surge removes it thus resuming meiosis I

what occurs in meiosis I

a secondary oocyte(haploid) and first polar body is formed. polar body is a cell with genetic material.

what occurs in meiosis II

oocyte is fertilized then undergoes another division. second polar body forms and resulting cell is a zygote

difference bwtween immature and mature oocyte

cumulus(granulosa cell surrounding oocyte) expands and first polar body is present