Estrus Cycle Flashcards
1
Q
Phases
A
3) proestrus
4) estrus
5) metestrus
6) diestrus
2
Q
Follicular phase
A
- follicles dominate ovary
- estrogen dominates
3
Q
Luteal phase
A
- corpus luteum dominates ovary
- progesterone dominates
4
Q
Proestrus
A
- follicle enlarges
- estrogen increases
- vascularity and endometrial glands inc
- estrogen levels peak
5
Q
Estrus
A
- allows male to mount
- estrogen decreases
- LH surge occurs
- ovulation after 24-48 hours of LH
- high uterine motility
- optimal sperm transport
- more cervical mucus volume
6
Q
Metestrus
A
- low estrogen
- corpus hemorrhagium
- ovulation in cow
- uterus
- less contraction
- endometrial glands grow and become coiled
- cattle: bleeding
7
Q
Diestrus
A
- progesterone high
- FSH low
- volume of fluid in uterus dec over time
- contractions stop
- cl regresses at end of this period of female is not pregnant
8
Q
Estrus in dog
A
- an estrus: has FSH to trigger follicular growth
- proestrus: estradiol inc and peaks; bloody discharge
- metestrus I: high progesterone, inc in estradiol (20 days)
- metestrus II: progesterone dec, estradiol dec, prolactin inc then declines
- inc in prolactin causes pseudo pregnancy
9
Q
Estrus cycle in a cat
A
- estrus is 9 days
- proestrus is 8 days
- repeats until mating occurs; mating induces LH surge, progesterone inc then dec, estrus returns after parturition when progesterone goes down
- low progesterone all the time
- estradiol is present during estrus
10
Q
Causes of anestrus
A
- pregnancy
- presence of offspring
- season
- stress
- pathology
11
Q
Types of anestrus
A
1) gestational
2) seasonal
3) lactational
4) nutritional
12
Q
Gestational anestrus
A
- normal
- CL present during pregnancy
- progesterone neg feedback on hypothalamus GnRH so no LH or FSH surge
- low estrogen-neg feedback also
- when CL regresses, hypothalamus doesn’t inc GnRH bc there’s no pos feedback from estradiol (useful bc it allows for uterine involution before first estrus cycle post partum
13
Q
Seasonal anestrus
A
- horses: long day (spring) breeders
- sheep: short day (fall) breeders
- anestrus to estrus: estradiol has neg feedback, switches to positive to trigger LH surge; like puberty
- estrus to anestrus: Progesterone dec, LH inc and estradiol inc, estradiol has positive feedback until LH surge
14
Q
Melatonin levels in seasonal anestrus
A
- less melatonin released in summer
- long day: respond to dec melatonin
- short day: respond to inc melatonin
15
Q
Lactational anestrus
A
- females suckling young
- Sow: completely suppresses anestrus
- cow: suppressed for up to 60 days
- frequency: 2 per day
- prolactin: inhibits GnRH release; too much prolactin=no milk
- not a sensory event
- suppression of GnRH and LH
