Female Reproductive Cycle- Lecture 6

Question 1

Luteolysis

Answer 1

The CL regressing if their is no pregnancy. Progesterone falls. PGF2alpha is released from edometrium and causes CL destruction.

Question 2

Anestrus

Answer 2

Anytime a female is not cycling. Can be due to: seasons, pregnancy, lactation, stress, or pathology.

Question 2

Short-day breeders

Answer 2

Sheep and goats. Cyclicity occurs during fall months. Decreased daylight causes increased melatonin. Melatonin stimulates secretion of GnRH in short-day breeders.

Question 2

PGF2alpha

Answer 2

Prostaglandin F2 alpha. Produced by endometrium. Destroys CL (luteolysis)

Question 3

Estrous cycle

Answer 3

Reproductive cycle of non-primate species. Period from one estrus cycle to the next. Has a follicular phase and luteal phase.

Question 4

FSH

Answer 4

Produced and released from anterior pituitary. Promotes follicular development in females. Stimulated by GnRH and inhibited by inhibin.

Question 4

Metestrus

Answer 4

Period of transition from estrus to diestrus. Time when CL is forming. Estrogen begins to fall and progesterone rises. Female is no longer receptive.

Question 5

LH

Answer 5

Produced and released from anterior pituitary. Causes follicular maturation and ovulation. Promotes development and maintenance of corpus luteum. Stimulated by GnRH and inhibited by progesterone.

Question 5

Estrogen

Answer 5

Produced by ovarian follicles. Causes estrous behavior and inhibits FSH. Once it reaches high enough levels it causes a surge in GnRH.

Question 7

Monoestrus

Answer 7

One estrus cycle a year. Wolves, foxes, bears, and dogs. Has an anestrus phase.

Question 8

Estrus

Answer 8

Period of behavioral receptivity during the estrous cycle. “Heat” or season. Estrogen from dominant follicle is high. Progesterone is low. Ovulation occurs.

Question 10

Polystrous

Answer 10

Repeated estrous cycles are uniformly distributed throughout the year. Cattle, swine, rodents.

Question 10

Progesterone (P4)

Answer 10

Produced by CL. It is essential for pregnancy maintenance. Inhibits estrous behavior and GnRH secretion.

Question 11

Diestrus

Answer 11

High progesterone. Uterus preparing for possible pregnancy. Female with refuse male. Follicles can develop but doesn’t ovulate.

Question 13

Seasonally polyestrous

Answer 13

Repeated estrous cycles for a portion of the year. Horses, sheep, goats, cats.

Question 15

GnRH

Answer 15

Synthesized and released from hypothalamus. Stimulates production and secretion of LH and FSH by the anterior pituitary.

Question 16

Long-day breeders

Answer 16

Horses. Cyclicity occurs in spring&summer months. Increased daylight causes decreased melatonin. Melatonin secretion inhibits GnRH in long-day breeders.

Question 18

Hypothalamic-pituitary-gonadal Axis

Answer 18

Hypothalamus (GnRH) –> Anterior Pituitary (LH and FSH) –> Ovary (inhibin, estrogen, progesterone)

Question 19

Proestrous

Answer 19

Begins when progesterone declines following luteolysis. Follicles are recruited and estrogen increases as they develop. Repro tract prepares for estrus & mating. Female doesn’t allow mating yet.

Question 20

Seasonal cyclicity

Answer 20

Seasonally polyestrous animals cycle only during a portion of the year. Give birth during environmental conditions that are favorable for neonatal survival. GnRH secretion is regulated by photoperiod and temperature. More darkness= more melatonin produced by pineal gland.

Question 21

Phases of estrous cycle

Answer 21

Follicular phase: where ovulation occurs, estrogen peaks. 20 % of cycle. Subdivided into proestrous and estrus. Luteal phase: 80% of cycle. Estrogen levels low, dominated by progesterone. Subdivided into metestrus and diestrus.