Estrous Cycle & Cyclicity

when estradiol reaches the brain, what effect does this have on the body?

increase lordosis (mating posture)

increase phonation

increase in physical activity

when estradiol reaches the reproductive tract, what effect does this have on the body?

increase blood flow

increase edema of tissues

increase mucous secretion

increase in leukocytes

increase in smooth muscle motility

increase growth of uterine glands

female in standing heat

estrus

sexual receptivity

estrus

what causes estrus?

large amount of estradiol being produced from follicles

the interval from the onset of one estrus (heat) until the onset of the next estrus

estrous cycle

estrous is …

adjective

estrus is …

a noun

high estradiol causes …. surge, which causes … surge, which ultimately causes … to occur

GnRH, LH, ovulation

when do females tend to ovulate in estrus?

end of estrus

GnRH pattern of secretion

episodic

characteristics of metestrus

lasts 1-5 days

all hormone levels are low

progesterone levels start to increase

what stage of estrous cycle when progesterone starts to increase?

metestrus

what stage of the estrous cycle could a female maintain pregnancy?

diestrus

characteristics of diestrus

CL fully functional

high levels of progesterone being produced and released

lasts 10-14 days

what helps to maintain pregnancy in diestrus?

no PGF2a being released from uterus to cause luteolysis

if there is no embryo in the uterus during diestrus, what occurs?

PGF2a causes the CL to regress (luteolysis)

when luteolysis occurs, what steroid hormone decreases and what hormone is removed?

progesterone, inhibin

which phase of the estrous cycle lasts the longest?

diestrus

release pattern of steroid hormones

sustained

if there are low levels of GnRH, what is also low? what does this cause?

LH and FSH, no follicle recruitment

as the levels of progesterone decrease, the … feedback on the hypothalamus … and GnRH levels gradually … , leading to the next generation of antral follicles to be recruited

negative, decreases, increase

characteristics of proestrus

CL is undergoing regression (luteolysis)

progesterone levels fall

lasts 1-3 days

in proestrus, what is the dominant hormone?

switches from progesterone dominance to estradiol dominance

what structure develops in proestrus?

antral follicle

during what phase of the estrous cycle does the female start to become receptive? what is this due to?

proestrus, estradiol

what does estradiol do in proestrus?

prepares the uterus and oviducts for sperm transport and fertilization

2 main phases of the estrous cycle

follicular and luteal

a phase of follicular development which begins when the CL regresses and ends with ovulation of the mature dominant and ovulatory follicles

follicular phase

what are the 2 stages of the follicular phase?

proestrus

estrus

stage of follicular phase

CL regression to heat

proestrus

stage of follicular phase

sexual receptivity

estrus

which phase of the estrous cycle is estrogen dependent

follicular phase

what phase of the estrous cycle is progesterone dependent

luteal phase

a phase of the estrous cycle that extends from the formation of the CL after ovulation until the CL regresses

luteal phase

stages of the luteal phase

metestrus

diestrus

stage of the luteal phase that is a transitory period following ovulation until CL is functional

metestrus

stage of the luteal phase that is the period during which CL is functional. Longest of the four stages

diestrus

when does ovulation occur in terms of the follicular and luteal phase?

the switch between the follicular phase and the luteal phase

during the switch from the follicular to luteal phase, the corpus hemorrhagicum becomes the …, which causes estradiol to … and progesterone to …

corpus luteum, decrease, increase

more specifically, when do you ovulate?

at the end of estrus phase

which animal has the shortest estrous cycle?

sheep

T/F

many small CL do not produce the same amount of progesterone as fewer large CL

true

what cycle do birds have?

ovulatory cycle

birds

no pregnancy means no … which means no … phase

CL, luteal

what is the culmination of follicular growth in hens?

ovulation

when will hens ovulate after oviposition

10-30 minutes after oviposition

process of laying an egg is called

oviposition

how often are eggs deposited

every 25-27 hours

T/F

hens will oviposit later each day

true

if an egg is oviposited late in the afternoon, what will occur?

no ovulation will occur and the hen will have a skip/pause day

what is the pattern of egg laying (from first oviposition through pause day)

sequence or clutch

young hen clutch

10-20 eggs

aged hen clutch

4-5 eggs

several estrous cycles that occur during a time period is a

season

many cycles

polyestrus

monoestrus

one cycle

not cycling

anestrus

what is the predominant hormone elevated during estrus?

estradiol

seasonal polyestrus (long day)

begins cycling as day length increases

won’t cycle through winter or fall

polyestrus

cycles throughout the year

seasonal polyestrus (short day)

begins cycling as day length decreases

cycle when it starts to get darker out

animals that hibernate are usually…

monoestrus

what hormone controls anestrus

GnRH

what factors cause anestrus

pregnancy

lactational

stress

seasonal

seasonal

pre-pubertal

before puberty, LH levels are

low

what 3 things can stimulate GnRH neurons

energy (blood glucose)

fat (blood leptin)

blood fatty acids

suckling stimulation inhibits … which causes anestrus

GnRH

what does the pineal gland release?

melatonin

precursor to melatonin

seratonin

what animals are long day seasonal polyestrus

mare

what animals are short day seasonal polyestrus

ewe, doe, elk

what animals are polyestrus

cow, queen, pig, rodents

what animals are monoestrus

dog (undomesticated), wolf, fox, bear