ANS 431 Exam 3

Atresia

the process by which follicles regress/die

* decreased estradiol and inhibin

tertiary

follicles grow to ________ characteristics and degenerate

gonadotropin sensitive

small antral follicles are ______ ________

recruitment

a small group of follicles is recruited from a larger pool of growing follicles

* increased FSH and estradiol (dominant hormones)

selection

a follicle is selected from the recruited pool to go on to the dominance phase. There is a continued growth of the largest follicle and a reduced growth rate of the smaller follicles

* decreased FSH
* increased estradiol and inibin

dominance

a follicle grows to pre-ovulatory size and causes smaller follicles to regress

* decreased FSH
* increased estradiol and inhibin (dominant hormones)

preovulatory

a mature dominant follicle acquires capacity to ovulate

ovulation

rupture of the follicle wall to release the oocyte to be collected by the fimbriae on the infundibulum and transported to the oviduct

follicular waves

group of follicles that grow and regress together during the estrous/menstrual cycle, pregnancy, or anestrous/transitional phase

FSH

controls emergence of follicles

* increase in FSH precedes emergence

Monovular

in _____ species usually one follicle establishes dominance, becomes ovulatory, and ovulates or regresses

progesterone

what hormone drops right before ovulation

cattle

2-3 follicular waves/cycle where the CL produces progesterone

Sheep

4-5 follicular waves/cycle where the CL produces progesterone

pigs

1 follicular wave/cycle where the CL produces progesterone

horses

1-3 follicular waves/cycle where the CL produces both progesterone and inhibin

human

1-3 follicular waves/cycle where the CL produces progesterone and inhibin

LH receptor

the ___ ____- _______ activates the cAMP which activates PKA that activates the transformation of cholesterol to testosterone__

FSH receptor

___ ___ binding on the granulosa cell activates cAMP that activates PKA to transform the testosterone from the theca cell to be transformed into estradiol.

estradiol

the ____ leaves the granulosa cell and enters the bloodstream

two cell theory

if the granulosa cell does not have an LH receptor the follicle will not be strong enough to establish dominance

LH receptor

dominant follicles express a __ ___ on the granulosa cell to supply extra cAMP.

proestrus and estrus

what phases of the estrous cycle are included in the follicular phase?

tonic

during the _____ release of GnRH , there is a negative feedback loop that occurs (GnRH → LH → Estradiol & LH); during this follicles (estradiol) and the CL (progesterone) inhibit the release of GnRH

GnRH surge

during the ______ surge, very high levels of estradiol produced by the pre-ovulatory follicle induce a positive feedback loop until ovulation (GnRH → LH → tons of estradiol from large follicle which then leads to positive feedback, increasing GnRH and LH release) leading to the preovulatory LH surge

decreased

as an animal ages, atresia leads to a drastic ______ in the total number of follicles (for calves at day 100 in utero: 2.9 million follicles; 1 year of age: 75,00; 10+ years: 2,500).

resisted

Atresia can be _____ in most species via superovulation using FSH

1-3

in monogastric species, inhibin controls the number of follicular waves per cycle, along with progesterone, to keep the number of waves to be between __*- usually*__

selection

after ____, the granulosa cells start to express the LH receptor. This means that even more testosterone (produced by the theca in the same manner as pre-selection) can be converted to estradiol, leading to more estradiol being produced and released into the blood

stigma

apex of the follicle that will be the first point of bursting

outermost to innermost layers

germinal epithelium → tunica albuginea → theca interna → basement membrane → granulosa cells → cumulus oophorus → corona radiata → oocyte

prevent ovulation

protein, steroid, prostaglandin, and plasminogen activator are the four types of synthesis that, when blocked, ____ ____

cumulus expansion

when the spaces between cumulus cells (in the cumulus oophorus) become filled with hyaluronic acid and proteins, making it “fluffier” and leading to separation of the cumulus-oocyte complex and the granulosa cells

copulation

leads to ovulation in an induced ovulating species.

sensory neurons

during intromission in induced ovulations, ___ __-______ in the vagina and cervix are triggered and induce production of GnRH from the hypothalamus, which leads to a surge of LH soon after copulation. Thus, ovulation will occur relatively soon after

primordial germ cells

after migration to the genital ridge in the embryo, ___ ____ will undergo mitotic divisions to create oogonia.

primary oocytes

Oogonia will start to undergo meiosis to become primary oocytes, which will arrest at prophase 1 of meiosis

granulosa cells

after prophase 1 is arrested, granulosa cells will form the primordial follicle around the primary oocyte, and hte oocyte and the follicle will start to grow (oocyte in size, follicle in size, cell type, etc.) together.

zona pellucida

as the oocyte grows, the _____ ___ will form around the oocyte. When the oocyte gets big enough and has the ____, the follicle surrounding the oocyte becomes gonadotropin dependent

primordial oocyte

a very early oocyte (primordial germ cell) that is capable of undergoing mitotic divisions and is only found during embryonic/fetal development

primordial follicle

an early stage of a follicle and contains a primary oocyte

cumulus-oocyte complex

cumulus oophorus → corona radiata → zona pellucida → oocyte

gap junction

a specialized intracellular connection that connects the cytoplasm of two cells and allows for cell-to-cell communication

meiotic arrest

the gap junctions are vital for the COC (between corona radiata granulosa cells and the oocyte, crossing through the zona pellucida) because they keep the oocyte in ___________ at prophase 1 before ovulation

cAMP

before the LH surge, gap junctions connecting the corona radiata and the oocyte exist. The granulosa cells of the corona radiata create _____, which can travel into the oocyte cytoplasm. Simultaneously, oocyte maturation inhibitor (OMI) in the oocyte also makes _____ . These. high levels of ______ lead to lots of activated PKA. which then goes and inactivates (via phosphorylation bc kinase) maturation promoting factor (MPF) into pre-MPF. Due to the low levels of MPF present in the oocyte (becomes most of it is inactivated pre-MPF), the germinal vesicle remains intact__

destroyed

after the LH surge, gap junctions are ______, so cAMP from the corona radiata cells cannot enter the oocyte. This leads to decreased levels of cAMP in the oocyte, which subsequently leads to decreased levels of PKA. PKA levels aren’t sufficient enough to keep converting MPF into pre-MPF, so pre-MPF is reverted back into MPF. At sufficient levels, MPF will cause breakdown of the germinal vesicle (GVBD). Meiosis will resume, leading to the release of the first polar body and eventual arrest at metaphase 2 (this is now a mature oocyte)

secondary/mature oocyte

after the LH surge, the primary oocyte (4N) resumes meiosis. The first polar body is released, and meiosis is arrested again at metaphase 2; the oocyte is now considered a ______/_____ (2N). This is what is ovulated in most species, and this is what the sperm penetrates for fertilization. After fertilization, meiosis resumes and the second polar body is released and the pronucleate egg (zygote) is formed.

polar body

the cellular byproduct of meiotic division of an oocyte; does not have the ability to become an oocyte despite being the product of cell division.

dogs and foxes

what species ovulate primary oocytes, where the sperm penetration occurs just prior to the release of the first polar body (right after meiosis resumes)

metestrus and diestrus

what phases of the estrous cycle are included in the luteal phase?

corpus luteum and progesterone

what are the dominant structure and hormone during the luteal phase of the estrus cycle?

rise

during metestrus when the CL is formed, progesterone levels _____ and continue to until about 1/3 of the way through diestrus. Once the CL is fully formed, progesterone production plateaus until luteolysis occurs, when progesterone levels sharply decrease

collagenase

the theca interna produce collagenase to weaken the follicular wall prior to ovulation

corpus hemorrhagicum

a structure potentially present 1-3 days post-ovulation where blood vessels in the follicle wall rupture and create a blood clot

corpus luteum

the progesterone-producing gland that forms from follicular cells after ovulation occurs.

small luteal cells

form theca cells

large luteal cells

derived from granulosa cells

secretory granules

structures within luteal cells that contain oxytocin and relaxin

vascularization

this is important for the CL because it affects steroid hormone synthesis and delivery in the CL. If the CL cannot function properly, there will be a failure to maintain pregnancy

mitochondria

this converts cholesterol into pregnenolone, which is vital for steroid hormone synthesis for proper CL function.

hypothalamus

progesterone targets the _____ and has a negative feedback GnRH release; it also affects the anterior pituitary to block LH release. Progesterone will also stop endometrial cells from producing PGF2a for about 12-14 days unless pregnancy occurs. Additionally, the progesterone from the CL will also target myometrial cells to stop uterine contractions (not in horses) to facilitate implantation and target the mammary glands to induce alveolar development.

luteal cells producing progesterone

LH binds to receptor → adenylyl cyclase activated to produce cAMP → cAMP activates PKA → PKA brings cholesterol into the cell → cholesterol enters the mitochondria → mitochondria converts cholesterol to pregnenolone →smooth endoplasmic reticulum converts pregnenolone into progesterone → progesterone leaves cell

luteolysis

lysis of the CL; the act the CL being converted in the non-secretory corpus albicans

PGF2a and oxytocin

important for luteolysis

ruminants

the uterus produces PGF2a, which is released into the uterine vein and is then picked up by the uterine artery, which wraps around the uterine vein. The PGF2a that is now the uterine artery can be picked up by the ovarian artery via counter-current exchange (through anastomosis of these two arteries), where the PGF2a can now be delivered to the ovary by the blood supply, where it can cause lysis of the CL.

mares

the uterine vein in mares is separate from the uterine artery, meaning that there is no direct interaction between the uterine vein and the ovarian artery . Thus, PGF2a must travel systemically before it reaches the ovary to cause lysis of CL

oxytocin

binding of _____ to receptors in the endometrium leads to production of PGF2a, which is required for luteolysis. At about day 14 of the estrous cycle, the amount of this hormone’s receptors present on the endometrium increases, and then deceases again just after ovulation (and this cycles, so again at around day 14, the receptor number will increase)

PGF2a

oxytocin is highly associated with ____; when oxytocin levels peak, this horomone’s levels also peak

The CL releases oxytocin from secretory granules in luteal cells while the endometrium (in the uterus) releases ____ from cells that have oxytocin receptors

cellular respons to luteolysis

the decreased blood flow (vasoconstriction) to the CL via PGF2a causes apoptosis of luteal cells via hypoxia (lack of oxygen). This causes a decrease in progesterone synthesis (because of apoptosis). Apoptosis of luteal cells also induces an immune response, so lymphocytes and macrophages come and “clean out” the CL, leaving fibroblasts in the end that create scar tissue: corpus albicans

how PGF2a affects luteal cells

PGF2a binds receptor on luteal cells → this activates PLC → PLC induces endoplasmic reticulum to make calcium and also activates PKC → PKC brings calcium into the cell and also inactivates conversion of cholesterol to progesteorne → high levels of calcium induce apoptosis while lack of progesterone leads to decreased production ability by the luteal cells

progesterone, estradiol, and PGF2a

a drop in ___ __and__ *and an increase of* ___ are all responsible for menstruation/menses.

PGF2a

increased _____ causes vasoconstriction, necrosis, endometrial inflammation, and tissue degeneration leading to the sloughing of the endometrium (menses)

lack of receptors

on days 1-4, the CL is not responsive to PGF2a because of ____--

regressed

on days 18-21, the CL is already ______ to much for PGF2a to really do anything

cut

PGF2a administration will ___ off any progesterone production due to CL lysis, which allows for ovulation of the follicular wave that was growing during the progesterone phase

ovsynch protocol

a method of synchronizing ovulation. One shot of GnRH to eliminate the current folilcular wave via ovulation induction) followed by administration of PGF2a 7 days later (to lyse the CL formed from the GnRH-induced ovulation), then followed by one last shot of GnRH 36-8 hours later to induce ovulation so that AI can occur 8-18 hours later

principle of progestin

protestins will maintain the cow under progesteronic influence until the CL regresses naturally, then continue to deliver progesterone to the cow. This is beneficial because once the CL has regressed naturally and the progestins stop being delivered to the animal, estrus and ovulation will occur soon after the progestin delivery stops.

behavior

the internally coordinated responses of whole living organisms to internal and external stimuli

puberty

the ability to detect a female in estrous or ability to display signs of estrus

linearly

sperm output increases _____ after puberty, then plateaus at just under 2 years in bulls

precopulatory

the acts of finding a mate up until the actual mating process

* search for sexual partner
* courtship
* sexual arousal

copulatory

act of mating

* mounting
* intromission
* ejaculation

postcopulatory

the acts after ejaculation when sexual partners separate

* dismounting
* refractory period: when the male will not be able to copulate after an ejaculation

females

only search for a sexual partner when they are in estrus

males

search for a sexual partner at any time

electroejaculator

fast, doesn’t require much training of the animal

expensive, lower quality of ejaculates due to increased seminal fluid and ejaculation of immature sperm

volume/appearance, motility, vigor, concentration, and morphology

how is semen evaluated before freezing?

nutrients, cold shock prevention/cryoprotectants, buffer, antibiotics, additives, water

what are typical components of semen extenders?

pre-dilution

gets the sperm to a different concentration before introducing sperm to the final freezing dilution

ewe

uses cervical, transcervical, and intrauterine AI

sow

uses intracervical and intrauterine AI

mare and cow

uses intrauterine AI only

laprascopic

since sheep can’t be rectally palpated and with the annular rings it makes traditional insemination very difficult, so _______ insemination is usually more successful

factors of conception

time of insemination, number of sperm inseminated, fertility of males, skill of inseminator

sperm path

seminiferous tubules → rete testis → efferent ducts → head/body/tail of epididymis → ductus deferens → pelvic urethra → penile urethra → vagina → external cervical os → cervix → internal cervical os → uterus → uterine horn → uterotubal junction → isthimus of the oviduct → ampullary -isthimic junction

decapacitation factor

added in the epididymis, where it works to stabilize the plasma membrane of the sperm (prevents premature capacitation)

oocyte path

develops in a follicle in the ovary → taken into oviduct by infundibulum → ampulla → ampullary-isthmic junction

vagina

the site of ejaculation in humans, rabbits, sheep, and cattle

uterus

site of ejaculation in horses

cervix or uterus

site of ejaculation for dogs and pigs