Reproductive Cyclicity in the Female Flashcards
1
Q
are estrus and estrous synonymous?
A
no, estrus is a noun and estrous is an adjective (the cycle)
2
Q
are estrus and heat synonymous?
A
yes
3
Q
what is anestrus?
A
when the female is not having repeated estrous cycles, usually normal causes
4
Q
what is polyestrus?
A
repeated cycles at regular intervals throughout the year
5
Q
what is seasonally polyestrus?
A
estrous cycles at regular intervals that depend on season, specifically day length
6
Q
when do short day seasonally polyestrus animals cycle?
A
in the fall in the northern hemisphere
7
Q
when do long day seasonally polyestrus animal cycle?
A
spring and summer in the northern hemisphere
8
Q
are seasonally polyestrus cycles more or less regulated as you move closer to the equator?
A
less regulated
9
Q
give the 3 types of cyclicity
A
- polyestrus
- seasonally polyestrus
- monoestrus
10
Q
define monoestrus
A
1-2 cycles per year, lots of species variation but cycles can average 6-8 months long
11
Q
how long is the cow reproductive cycle?
A
21 days long
12
Q
why type of cyclicity do cows have?
A
polyestrus
13
Q
how long is estrus for cows?
A
12-18 hours
14
Q
when do cows ovulate?
A
11 hours AFTER estrus
15
Q
how long is pregnancy for cows?
A
282 days
16
Q
what type of cyclicity do ewes/goats have?
A
seasonal short day breeders (in the fall)
17
Q
how long is the ewe/goat reproductive cycle?
A
17 days
18
Q
how long is estrus for ewe/goat?
A
24-36 hours
19
Q
when do ewes/goats ovulate?
A
near end of estrus
20
Q
how long is ewe/goat pregnancy?
A
148 days
21
Q
what type of cyclicity do sows have?
A
polyestrus
22
Q
how long is the sow repro cycle?
A
21 days
23
Q
when do sows ovulate?
A
35-45 hours after start of estrus
24
Q
how long is sow estrus?
A
48-72 hours
25
how long is sow pregnancy?
115 days
26
what type of cyclicity do mares have?
seasonally polyestrus, long day (spring) breeders
27
how long is estrus for mares?
5-7 days
28
when do mares ovulate?
days 3-6 of estrus, 1-2 days before the end of estrus
29
how long is pregnancy for mares?
335-340 days
30
how long is the estrous cycle of a bitch?
6 months
31
how long is estrus for a bitch?
9 days
32
when do bitches ovulate?
4-24 days after start of estrus
33
how long is a bitch's pregnancy?
63 days
34
how long is the estrous cycle of a queen?
17 days
35
how long is estrus for a queen?
9 days
36
when do queens ovulate?
they are induced ovulators
37
how long is a queen's pregnancy?
63 days
38
when referring to cycle type, what does spontaneous mean?
happens regardless of mating
39
when referring to cycle type, what does induced mean?
requires mating in order to occur
40
are phases and stages of the estrous cycle the same?
NOOOOO
41
list the 2 PHASES of the estrous cycle
1. follicular phase
| 2. luteal phase
42
describe the follicular phase of the estrous cycle, incluing what dominates the ovarian structure and what the dominant hormone is
follicles dominate ovarian structure, dominant hormone is estrogen
43
describe when the follicular phase of the estrous cycle occurs
from regression of the previous CL to approximately ovulation
44
in cattle, how much of the estrous cycle is taken up by the follicular phase?
about 20%
45
describe the luteal phase of the estrous cycle, including what dominates the ovarian structure and what the dominant hormone is
corpora lutea dominant ovarian structure, progesterone is dominant hormone
46
when does the luteal phase of the estrous cycle occur?
from ovulation until CL regression (if no baby)
47
how long of the cattle estrous cycle is take up by the luteal phase?
about 80%
48
how many stages are in the estrous cycle?
4
49
which two stages of the estrous cycle occur during the follicular phase?
proestrus and estrus
50
which two stages of the estrous cycle occur during the luteal phase?
metestrus and diestrus
51
describe proestrus, including length
the stage that immediately precedes estrus (heat), 2-5 days long depending on the species
52
describe what is happening in terms of steroid hormones during proestrus (3)
1. stage begins when P4 levels start to decline due to leutolysis of previous CL
2. major endocrine transition from P4 dominance to E2 dominance
3. net increase in E2
53
describe what is happening in the ovary during proestrus (3)
1. preovulatory follicle is enlarging
2. antrum is getting larger in diameter
3. granulosa cells producing more and more E2
54
describe what is happening in the repro tract during proestrus (2)
1. endometrial gland growth in uterus
| 2. more cilia in oviduct
55
what percentage of the reproductive cycle is taken up by the follicular phase? in cattle
about 20%
56
what dominates the ovrian structure in the follicular phase?
ovarian follicles
57
what is the dominant hormone during the follicular phase?
estrogen, E2
58
what events mark the beginning and end of the follicular phase?
goes from regression of previous CL until approximately ovulation
59
what percentage of the repro cycle is taken up by the luteal phase in cattle?
about 80%
60
what dominates the ovarian structure during the luteal phase?
corpora lutea
61
what is the dominant hormone during the luteal phase?
progesterone
62
what events mark the beginning and end of the luteal phase?
from ovulation until CL regression if animal is not pregnant
63
broadly define estrus (2)
1. behavioral change in female to be more receptive to mating
2. standing heat
64
describe what is happening in terms of steroid hormones during estrus (1)
E2 decreases during this stage
65
describe what is happening in terms of gonadotropins during estrus (1)
LH surge due to high E2 levels from proestrus
66
describe what is happening to the ovary during estrus (1)
24-48 hours after LH surge, pre-ovulatory follicle will ovulate
67
when do cattle ovulate?
during metestrus
68
describe what is happening with the repro tract during estrus (2)
1. uterine motility is high due to muscle contractions, which contract toward oviduct for optimal sperm transport
2. high levels of cervical mucus, especially in mares and ruminants like cattle
69
what is metestrus?
the time between ovulation and functional CL formation
70
describe what is happening in terms of steroid hormones during metestrus (1)
E2 and P4 are low
71
describe what is happening in terms of gonadotropins during metestrus (1)
increase in FSH will initiate new waves of follicles, due to increased negative feedback from E2 and inhibin
72
describe what is happening in the ovary during metestrus in CATTLE
ovulation in CATTLE only
73
describe what is happening in the repro tract during metestrus (2 and then 1 just for cattle)
1. decreased uterine contractions
2. endometrial gland growth and secretions, endometrial glands are becoming coiled in appearance
3. may see bleeding in cattle, diapadesis
74
what is diapadesis?
leaky vasculature
75
what is diestrus?
the longest stage of the cycle
76
when does diestrus begin?
at P4 production
77
describe what is happening in terms of steroid hormones during diestrus?
HIGH P4
78
describe what is happening in terms of gonadotropins during diestrus
FSH increases and decreases, creating new follicular waves
79
describe what is happening in the repro tract during diestrus
1. initially uterine contractions and secretions are very high
2. as diestrus progresses, uterine contractions and secretions will decrease
3. P4 quiets the uterus, decreasing uterine contractions
4. if animal is NOT pregnant, uterus will produce PGF2a, which lyses CL and animal will go back into proestrus
80
how long is the menstrual cycle?
28 days
81
what is day 0 of the menstrual cycle?
the first day of menses (bleeding)
82
on what day of the menstrual cycle does ovulation occur?
day 14
83
in the menstrual cycle, how long do follicular and luteal phases last?
SAME amount of time, 14 days each
84
how long, on average, does proestrus last in bitches? what is the range?
7-10 days, can range from 4-20 days
85
how long on average does estrus last in bitches? what is the range?
9 days, can range from 3-21 days
86
describe estrus in bitches (5)
1. E2 decline, LH surge
2. ovulation towards end of estrus
3. female will allow mating
4. maximum keratinization
5. P4 increases prior to ovulation
87
describe proestrus in bitches (4)
1. E2 increasing, peaks at end
2. swelling of vulva
3. vaginal, bloody discharge (diapadesis)
4. keratinization increases in vaginal epithelium for protection, can be used to determine appropriate breeding times
88
describe metestrus in bitches
absent
89
how long does diestrus last in bitches?
70-80 days, makes up entire luteal phase
90
when does diestrus begin in bitches?
about 6 days post ovulation
91
describe what is happening in terms of steroid hormones in bitches during diestrus
1. P4 begins very high and then starts to decline
| 2. if bitch is not pregnant, P4 drops and a pseudopregnancy can be observed
92
when does diestrus end for bitches in terms of steroid hormones?
stage ends when P4 drops to less than 1ng/mL, usually prior to whelping if bitch is pregnant
93
describe what is happening in the repro tract during diestrus for bitches
uterus is not active in CL regression, meaning it does not release PGF2a to lyse the CL, so the CL will last entire length of a pregnanct, even if bitch is not pregnant (pseudopregnancy)
94
how long is anestrus on average for bitches? what controls the extreme variation?
4-6 months, highly variable; genetics and environment control length of this stage
95
when referring to a queen, what is interestrus?
diestrus + anestrus
96
what happens behaviorally during estrus in a queen?
they will vocalize, assume lordosis position, restless
97
describe the lordosis position in a queen
arched back
98
if a queen is not mated, what stage occurs?
post estrus
99
what happens in post estrus in queens? (3)
1. no ovulation
2. E2 declines, P4 also low
3. new follicular wave begins
100
if a queen is mated, what follows? (4)
1. LH surge is induced
2. ovulations of multiple follicles
3. CLs cause high P4
4. uterus will not release PGF2a, so a pseudopregnancy can occur if mating was unsuccessful and not pregnant
101
if a queen is mated but not pregnant, when will P4 return back to normal levels?
after approximately the same number of days as gestation
102
what percentage of queens will ovulate after breeding?
50%
103
when will peak LH surge ovulations occur in terms of queens and number of matings?
peak LH ovulations will occur with 8-12 matings of short duration, as queens are induced ovulators
104
list 3 normal causes of anestrus
1. pregnancy
2. season
3. presence of offspring
105
list 3 abnormal causes of anestrus
1. inadequate nutrition
2. stress
3. pathology
106
List the 4 types of anestrus
1. gestational anestrus
2. seasonal anestrus
3. lactational anestrus
4. nutritional anestrus
107
what causes gestational anestrus?
progesterone from pregnancy exerts negative feedback on the hypothalamus
108
why does gestational anestrus continue after pregnancy?
due to the long progesterone exposure during pregnancy, the hypothalamus lacks estradiol positive feedback
109
what is the reason for gestational anestrus continuing for a while after pregnancy?
allows for uterine involution
110
what does the sheep seasonal anestrus cycle line up with?
when forage is available and of good quality
111
describe the 5 steps of day length affecting cyclicity of a sheep (short day breeders) during long day seasons
1. increased light will act on receptors in retina
2. receptors communicate with pineal gland; cause a decrease in melatonin production
3. decreased melatonin signal to hypothalamus to decrease GnRH secretion
4. this decreases FSH and LH levels
5. this decreases gonadal stimulation to pause cyclicity
112
describe the 5 steps of day length affecting cyclicity of a horse (long day breeder) during long day seasons
1. increased light will act on receptors in retina
2. receptors communicate with pineal gland; cause a decrease in melatonin production
3. decreased melatonin signals to hypothalamus to INCREASE GnRH secretion
4. this increases FSH and LH levels
5. this increases gonadal stimulation to resume cyclicity
113
what is silent ovulation?
ovulation without behavioral heat
114
what does the brain need in order to express estrus in response to estrogen?
it must first be primed with progesterone
115
when is silent ovulation common?
in first ovulation after a period of anestrus
116
list a describe the 2 types of E2 receptors in the hypothalamus
1. receptors for surge: don't need P4 to work
| 2. receptors for behavior: have to have been exposed to P4 to work
117
what animal has a very high degree of lactational anestrus?
pigs
118
describe the effect of suckling on LH secretion
as suckling decreases, LH secretions increase to resume cyclicity
119
list the 3 general factors that relate to lactational anestrus
1. suckling
2. other offspring factors
3. prolactin
120
what are the three offspring factors that affect lactational anestrus?
1. visual encounter
2. olfactory encounter
3. auditory encounter
121
what can excess prolactin do to humans?
lead to infertility
122
what happens to males (fathers) when offspring are born in response to cues and why?
excess prolactin production, leads to paternal bonding
123
what is the right window to avoid nutritional anestrus?
right between too low and too high body fat
124
what causes body fat to be too low and what is the result?
nutritional deficit leads to nutritional anestrus
125
what happens when body fat is too high and what is the result?
disregulation of metabolism, nutritional anestrus
