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Ch. 7 - Reproductive Cyclicity - Coggle Diagram
Ch. 7 - Reproductive Cyclicity
Estrous Cycle
Each cycle consists of a follicular phase and a luteal phase
Follicular Phase:
dominated by estradiol secreted by ovarian follicles
Estradiol causes marked changes in the female tract and initiates sexual receptivity
Large antral follicles are present - primary ovarian structure
Estradiol (secreted by follicles) is the primary hormone
Proestrous and estrus
Luteal Phase:
dominated by progesterone from the corpus luteum that prepares the reproductive tract for pregnancy
Corpora lutea is the primary ovarian structure
Progesterone (secreted by corpora lutea) is the primary hormone
Metestrus and diestrus
Consists of the physiologic events that occur between successive periods of sexual receptivity (estrus or heat) and/or ovulations
Anestrus:
periods of time when estrous cycles cease
Causes:
Season of the year
Lactation
Pregnancy
Certain forms of stress
Includes nutritional stress - lack of proper nutrition
Pathology
Apparent Anestrus:
failure to detect estrus or failure to recognize pregnancy
True Anestrus:
insufficient hormonal stimuli
Gestational Anestrus:
normal condition brought about by inhibition of GnRH by progesterone
Seasonal Anestrus:
prevents females from conceiving during periods of the year when survival of the developing embryo and the neonate would be low
Lactational Anestrus:
prevents a new pregnancy before young are weaned
Estrous:
adjective - pertaining to estrus
Estrus:
noun - period of sexual receptiviy
Three types of estrus cyclicity
Seasonally Polyestrous:
dislpay clusters of estrous cycles that occur only during a certain season of the year
Short day breeders
Sheep and goats
Long day breeders
Horses
Monoestrous:
have only one cycle per year
Polyestrous:
cycle throughout the year
Divided into 4 stages
Estrus
Sexual receptivity and peak estradiol secretion
When the female allows copulation
Metestrus
CL formation and begining of progesterone secretion
Transition from estradiol dominance to progesterone dominance
Proestrus
Period immediately preceding estrus
Formation of ovulatory follicles and estradiol secretion
Diestrus
Sustained luteal secretion of progesterone
Period of maximum luteal function
Menstrual Cycle
At the conclusion of the luteal phase in the menstrual cycle, the endometrium is sloughed to the exterior (menstration)
Consists of the physiological events that occur between successive menstrual periods
3 distinct phases that reflect the condition of the uterine endometrium
Phase 2 - Proliferative Phase:
follicles develop and secrete estradiol
The endometrium begins to grow and increases in thickness
Phase 3 - Secretory Phase
dominated by the corpus luteum that secretes progesterone and estradiol
Endometrium grows and thickens in response to progesterone
Luteal phase
Phase 1 - Menses:
endometrium is sloughed to the exterior
Follicular phase
Amenorrhea:
lack of menstrual periods from the same causes as anestrus
Differences from estrous cycle
A period of endometrial sloughing called menstration
The timeline for description of the cycle begins with menses, not ovulation or estrus
No defined period of sexual receptivity