test 2 (2): chapter 7 Reproductive Cyclicity Flashcards

A complete set of vocabulary flashcards covering reproductive cyclicity concepts, estrous types, cycle phases and stages, endocrine control mechanisms, species-specific variations, and menstrual cycle comparisons.

Estrous Cycle

The entire period of time from one estrus (heat) all the way until the next estrus or heat.

Polyestrous Species

Species that experience regularly occurring estrous cycles throughout the entire $12\,\text{month}$ year, such as cows with a $21\,\text{day}$ cycle and rodents with a $4\,\text{to}\,5\,\text{day}$ cycle.

Seasonally Polyestrous Species

Species that exhibit multiple estrous cycles within a specific season of the year, categorized into long-day breeders and short-day breeders.

Long-Day Breeders

Seasonally polyestrous species, such as mares, that begin cycling in the spring when day length is increasing.

Short-Day Breeders

Seasonally polyestrous species, such as ewes, does, and deer, that begin cycling in the fall when day length is decreasing.

Monoestrous Species

Species that experience only one estrous cycle per year, such as dogs, wolves, and bears.

Follicular Phase

The phase of the estrous cycle dominated by growing follicles and estrogen production, extending from luteolysis to ovulation.

Luteal Phase

The phase of the estrous cycle dominated by the corpus luteum and progesterone production, extending from ovulation to luteolysis.

Estrogen

The predominant steroid hormone produced by growing and dominant follicles during the follicular phase of the estrous cycle.

Progesterone

The predominant steroid hormone produced by the corpus luteum during the luteal phase of the estrous cycle.

PGF2 Alpha

A hormone produced by the uterus in non-pregnant females that induces luteolysis, leading to the destruction of the corpus luteum.

Proestrus

The stage of the follicular phase prior to estrus, characterized by the growth of tertiary or antral follicles and rising estrogen levels.

Estrus

The stage of the follicular phase characterized by a dominant follicle, peak estrogen levels, and standing behavioral heat.

Metestrus

The initial stage of the luteal phase following ovulation, during which the corpus hemorrhagicum transitions into a corpus luteum and progesterone levels begin to rise.

Diestrus

The longest stage of the estrous cycle by days, characterized by a fully functional corpus luteum and maximum progesterone levels.

AM/PM Rule

An artificial insemination timing rule in cows where cows observed in heat in the morning are inseminated in the afternoon, and those seen in heat in the afternoon are inseminated the next morning.

Mare Artificial Insemination Timing

The practice of monitoring mare follicular growth via ultrasound and inseminating when the dominant follicle reaches between $35\,\text{mm}$ and $40\,\text{mm}$ in size.

Anestrus

A period of time during which a female is not experiencing regular estrous cyclicity, caused by factors such as season, pregnancy, severe stress, poor body condition, or lactation.

Silent Ovulation

An ovulatory event without behavioral estrus that occurs as a female comes out of anestrus, caused by a lack of estrogen receptors in the behavioral center of the brain.

Progesterone Priming

The mechanism by which progesterone from the corpus luteum formed after a silent ovulation acts on the behavioral center of the brain to upregulate estrogen receptors for subsequent cycles.

Bitch Luteal Phase Mechanism

The physiological condition in the bitch where the luteal phase lasts $60\,\text{to}\,61\,\text{days}$ (equal to gestation length) regardless of pregnancy due to the absence of a uterine PGF2 alpha luteolytic mechanism.

Induced Ovulator

A species, such as the queen (feline), that will not ovulate unless copulation occurs to stimulate sensory neurons in the vagina via penile spines.

Post Estrus

A stage in the non-mated queen's cycle following estrus where unovulated follicles regress, resulting in low estrogen and low progesterone levels.

Melatonin

A hormone secreted by the pineal gland during darkness that translates photoperiod signal length to regulate seasonal cyclicity via Kisspeptin and GnRH neurons.

Lactational Anestrus

The suppression of GnRH pulsatility, LH pulsatility, and estrous cyclicity driven by frequent suckling sessions and close physical/social mother-offspring contact during lactation.

Foal Heat

A fertile heat occurring in mares shortly after foaling ($30\,\text{to}\,35\,\text{days}$ window to maintain a yearly foaling interval) enabled by a less invasive placenta and reduced sensitivity to lactational anestrus.

Menstrual Cycle

A $28\,\text{day}$ reproductive cycle in primates characterized by equal $14\,\text{day}$ follicular and luteal phases, menses at day $0$, and no restricted period of sexual receptivity.

Menses

The period of sloughing off of the endometrial lining of the uterus occurring over $2\,\text{to}\,5\,\text{days}$ at the start of the menstrual cycle.

Proliferative Phase

The uterine phase corresponding to the follicular phase of the menstrual cycle during which the endometrial lining regrows.

Secretory Phase

The uterine phase corresponding to the luteal phase of the menstrual cycle during which uterine glands actively secrete fluids to support potential embryonic development.