Female Estrous Cycle/ Intro to Follicle Development Flashcards
Primordial follicles have what cell type?
squamous
Primary cell types have what cell types?
cubodial
What is the ESTROUS CYCLE?
series of predictable reproductive events that begin at estrus and continues until the subsequent events
What is estrus? heat.
noun. period when female is receptive to copulation with the male
what is Estrous?
adj. the length of the estrous cycle in the pig is 21 days
What is anestrus?
without cyclicity: ovaries are relatively inactive, neither ovulatory follicles or corpora lutea are present (pregnant/ right after birth/ before puberty)
What are the types of estrous cycles?
-Polyestrus: uniform distribution of estrous cycles throughout the year
-seasonally polyestrus: (sheep/horses)
clusters of estrous cycles that occur during certain seasons of the year
-monoestrus: only one cycle per year (dogs/wolves)
What is the follicular phase?
follicle is the dominant structure on the ovary
-proestrus+estrus
-Large antral follicles
-estrogen is secreted by the follicles (main hormone)
What is the Luteal phase?
C.L is the dominant structure on the ovary
-metestrus+diestrus
-progesterone secreted by the CL is the primary hormone
What is folliculogenesis? Species number?
some primordial follicles begin to grow continuously throughout life
-swine (10-25)
-sheep (1-3)
-cattle, horses, humans=1
What is the primary hormone produced by the follicle?
estrogen
What is the primary hormone produces by the C.L?
progesterone
What blocks the animal from going into heat?
progesterone
Describe a basic overview of follicular waves
-cohort of follicles recruited initially
-some of these will continue to develop , while others undergo atresia
-a dominant follicle is selected for continued growth to preovulatory size
-if this follicle achieves dominance around the time of luteolysis, it will ovulate
At the time of recruitment, what stage are the follicles in?
tertiary, just small
What is the StAR protein?
Steroidogenic acute regulatory protein, transport protein that transfers cholesterol into the inner mitochondrial membrane
- this is the RATE LIMITING step for steroidogenesis
What is happening to the levels of estrogen during the growth of the follicles?
with the highest quality follicle, more estrogen is produced
When does ovulation occur?
when progesterone declines, end of luteolysis (regression of the C.L)
What is happening in metestrus?
Luteal phase, right after ovulation form the previous cycle, corpus medi. here
What is happening in the Diestrus phase?
The C.L is mature, Producing max amount of progesterone, majority of the cycle
What is happening in proestrus?
progesterone declines, no signs of sexual reset
What happens on the last follicular wave?
occurring after luteolysis, results in a dominant follicle that will ovulate. Only those follicles recruited during or after luteolysis will become eligible for ovulation. Follicles from any wave that are in the growth phase when luteolysos occurs are capable of ovulation.
What happens to follicles during peak progesterone?
they become atretic
What happens during recruitment (hormones/brain)
entry into gonadotropin sensitive pool, Anterior Lobe is producing alot of FSH, little LH on the ovary. The ovary is producing estrogen (negative feedback on the surge center)
-LH on theca cells, no FSH receptor on granulosa cells
-FSH plays a more important role than LH in antral follicle growth
What happens during selection (brain/hormones)
some granulosa cells have gained LH receptors, FSH production has decreased, follicles producing estrogen and now inhibin (negative feedback on the surge center of the hypothalamus)
-estrogen acts on the Anterior Lobe, to stop production of FSH
What happens during dominance in a follicle (hormones)
The largest follicles produce more and more estrogen, this prompts a surge of LH. FSH secretion is low due to inhibin and estrogen are secreted in high levels by the dominant follicle
-The drop in FSH is believed to cause other antral follicles to undergo atresia
-Estrogen production is at the highest
How is the antrum formed?
from the stimulation of FSH, small pockets form together
List the layers of the ovary from outer to inner.
germinal epithelium, tunica albuginea, ovarian cortex,
ovarian medulla
Where is the site of fertilization?
ampullary-isthmuc junction
what are theca externa cells
outermost layer of the tertiary follicle that helps support integrity and growth
What are theca interna cells
layer of cells bordering the exterior portion of the basement membrane that are important for producing androgens like testosterone
What is the basement membrane
provides structural support to the developing follicles, maintaining cellular organization
What are granulosa cells
layer of cells bordering the interior portion of the basement membrane that are important for producing estrogen
What are corona radiata?
specialized granulosa cells that are in direct contact with the oocyte
what is the stroma layer?
connective tissue of the ovary
How long is the cow’s estrous cycle, duration of estrous, and timing of ovulation?
21 days, 15 hours, 24-32 hours
How long is the mare’s estrous cycle, duration of estrous, and timing of ovulation?
21 days, 7 days, 5 days
How long is the sow’s estrous cycle, duration of estrous, and timing of ovulation?
21 days, 50 hours, 36-44 hours
How long is the ewe’s estrous cycle, duration of estrous, and timing of ovulation?
17 days, 30 hours, 24-30 hours
why would anestrus occur?
prepubertal, pregnant, anorexic/obese, shortly after parturition, sickness/illness
What is the period immediately preceding estrus, give characteristics of this phase
proestrus
-formation of ovulatory follicles/ e2 secretion main hormone
-begins when progesterone declines
-a part of the follicular phase
What is estrus?
sexual receptivity and peak estrogen secretion
-female allows for copulation
-visual behavioral signs
What is metestrus?
CL formation+ beginning of progesterone secretion
-transition from estrogen to progesterone dominance
-formation of corpora lutea
What is diestrus?
-sustained luteal secretion of progesterone
-period of maximum luteal function
-longest stage of the estrous cycle and is a time when the corpus luteam is fully functional
-progesterone secretion is at the the highest
What are the normal stages of estrous?
estrus, metestrus, diestrus, proestrus, estrus
What is anestrus?
-means without heat or estrus
-result of insufficient GnRH release from the hypothalamus to stimulate and maintain gonadotropin secretion
