ANSC 3600: Reproductive Cyclicity (Exam 3;End of Chapter 7)

At what stage in estrus do P4 levels start to rise?

Metestrus

Which stages of estrus are included in the luteal phase?

Metestrus;diestrus

At what stage in estrus does P4(progesterone) start to decline?

Proestrus

What stage does E2 levels start to ascend?

Proestrus

When is the highest breeding activity in short day breeders?

September-January

How are short day breeders better adapted for breeding activities in Sept.-Jan.

Short day breeders breed when days are shorter and nights are longer. If nights are longer then more melatonin is produced. When more melatonin is produced more GnRH is produced and when more GnRH (increased GnRH neuron activity/pulse frequency)

What is seasonal anestrus characterized by?

(1)perception of ratio of daylight:dark (2)relative dormancy of GnRH secretions (3)minimal FSH and LH secretion

What are the effects of increased estrogen levels?

(1)prepares reproductive tract (2) sexual receptivity (3)induction of the LH surge (4)ovulation

At what stage(s) of estrus will you see the highest levels of FSH?

Anestrus with a spike in FSH at the start of estrus.

At what stage in estrus is E2 lowest?

Diestrus

At what stage in estrus is P4 highest?

Diestrus

At what stage in estrus is E2 levels highest?

Estrus

Follicular Phase: When GnRH increases, ________,___________ levels increase.

FSH, LH

Follicular Phase: When P4 production form the corpus luteum decreases ___________ increases.

GnRH

Why is inhibin put into effect during follicular growth?

Inhibin inhibits the actions of FSH. FSH is put into effect at the before follicular growth to support the growth of the ovarian follicular pool. As recruitment and selection occurs, inhibin is put into effect to stop the support of other non-dominant follicles.

Follicular Phase: when proestrual follicular development occurs, ____________________ is produced to reduce the production of _________.

Inhibin is produced to reduce the production of FSH

What are some characteristics (concerning type of ovulators and estrus cycle) about feline reproductive cyclicity?

They are polyestrus and induced ovulators

Why is the spring ideal for long day breeders?

Unlike short-day breeders, long day breeders respond to shorter nights (thus less melatonin) by producing more GnRH.

When does FSH increase once in estrus?

When ovulation is complete?

What phase do felines lack mostly?

a luteal phase

When does the corpus luteum develop in felines?

after copulation

Follicular Phase: Proestrual follicular development results in an increase in _________________ which stimulates preovulatory LH surge.

estradiol (E2)

Follicular growth drives an increase in

estrogen and inhibin

Felines have a constant ______________ phase.

follicular phase

What happens to short day breeders in the spring?

in the spring, the days are longer thus there is less melatonin and less GnRH frequency.

What is lactational anestrus and what is the traditional view of its cause?

it is a period of non-cyclicity spend during nursing and is blamed on baby stimulating nerves during suckling that causes cycling to stop.

What brain centers are involved in lactational anestrus?

olfactory, visual, auditory

Follicular Phase: What occurs when FSH and LH levels increase?

proestrual follicular development

What stages of estrus are included in the follicular phase?

proestrus and estrus

What is the path (neurally) of signal detecting relative length of the day/night (photoperiod)

signal --->retinohypothalamic tract---> suprachiasmatic nucleus of hypothamalamus (cranial) --> superior cervical ganglion --->pineal gland

When is the LH surge and what induces it?

the LH surge occurs right before ovulation and is induced by an increase in E2.

What is seasonal anestrus and why does it occur?

the time of the year when seasonal breeders are unreceptive; believed to prevent breeding of female when subsequent birth would be detrimental offspring