Therio - Estrous Cycle

Front 1

Estrus
-define

Back 1

(n.) period of sexual excitability when a female will accept the male for breeding

Front 2

Estrous
-define

Back 2

(adj.) relating to or a characteristic of estrus

Front 3

Estrous cycle
-controlled by

Back 3

-hypothalamic-pituitary-gonadal axis

-pineal gland secretion of melatonin control for animals reliant on photoperiod

Front 4

Species considered to not have an estrous cycle

Back 4

-rabbit
-considered in estrus at all times
-ovulate 10-13 hrs after copulation

Front 5

Estrous cycle
-frequencies

Back 5

-continually polyestrous
-seasonal polyestrous
-diestrous
-seasonally monoestrous

Front 6

Continually polyestrous
-define

Back 6

-have estrous cycles throughout the year as long as they are not pregnant

Front 7

Continually polyestrous
-spp

Back 7

-cattle
-pigs

Front 8

Seasonal polyestrous
-define

Back 8

-have multiple estrous cycles during part of the year, but are anestrous for part of the year

Front 9

Seasonal polyestrous
-determined by

Back 9

-day length(photoperiod)

Front 10

Seasonally polyestrous
-spp

Back 10

Short-day breeders:
-sheep
-goat
-cervids (deer)

Long-day breeders:
-horse
-cat
-hamster

Front 11

Long day breeders
-define

Back 11

-breed in the spring
-born in the spring

Front 12

Short day breeders
-define

Back 12

-breed in the fall
-born in the spring

Front 13

Diestrous
-define

Back 13

-go into estrus twice per year

Front 14

Diestrous
-spp

Back 14

-dog

Front 15

Seasonally monoestrous
-define

Back 15

-one estrous cycle per year normally during a specific season

Front 16

Seasonally monoestrous
-spp

Back 16

-African breed dogs
-bears
-wolves
-foxes

Front 17

Bovine estrous cycle
-main periods

Back 17

-estrus
-metestrus
-diestrus
-proestrus

Front 18

Bovine
-modal length of estrous cycle

Back 18

-cow: 21 days
-heifer: 20 days

Front 19

Hormone in control of estrous behavior

Back 19

-progesterone

Front 20

Follicular growth in cows
-describe

Back 20

-at beginning of the cycle there is a cohort of follicles
-eventually a dominant follicle emerges from the pack and inhibits the other follicles from the cohort

Front 21

Bovine estrus
-presentation

Back 21

-standing to be mounted

Front 22

Bovine estrous
-lasts how long

Back 22

-20 hrs

Front 23

Bovine estrous
-hormone levels

Back 23

-progesterone low (CL has been lysed)
--needs to be low for estradiol to induce a GnRH surge

-estrogen falling

Front 24

Bovine metestrous
-presentation

Back 24

-no longer standing to be mounted

Front 25

Bovine metestrous
-what occurs

Back 25

-ovulation occurs
-CL undergoes early development

Front 26

Bovine metestrous
-when does ovulation occur

Back 26

-10-15 hrs after estrous

Front 27

Bovine metestrous
-lasts how long

Back 27

-3-5 days

Front 28

Bovine metestrous
-hormonal control

Back 28

Day 1
-FSH dec.
-follicle growth continues

Day 2
-progesterone inc.
-FSH basal
-dominant follicles inhibit small

Day 3
-dominant secrete estradiol and inhibin

Day 4
-CL size and progesterone conc. inc
-large follicle divergence with subordinate atresia
-dominant follicle acquires LH receptors

Day 5
-PGF2a not very effective at lysing CL
-large estrogen dose is effective luteolytic agent

Front 29

What would happen if the largest growing follicle were ablated?

Back 29

-the largest subordinate follicle would become dominant

Front 30

What would happen if there was a GnRH surge right when the dominant follicle gained LH receptors?

Back 30

-ovulation but no nothing else due to high progesterone levels from CL

Front 31

Bovine diestrous
-define

Back 31

-period of CL dominance

Front 32

Bovine diestrous
-lasts how long

Back 32

-12 days

Front 33

Bovine diestrous
-hormone levels

Back 33

-high progesterone
-PGF2a can lyse CL (estrogen can't)

-GnRH induced LH will ovulate new dominant follicle

Front 34

Bovine proestrous
-define

Back 34

-CL regressing

Front 35

Bovine proestrous
-lasts how long

Back 35

-2-3 days

Front 36

Bovine proestrous
-hormone levels

Back 36

-decreasing progesterone
-increasing estrogen (w/ LH positive feedback)

-PGF2a has no effect (CL already regressing)

Front 37

On an ultrasound exam of a cycling cow, you did not find a large dominant-sized follicle. What stage of he estrous cycle is the cow?

Back 37

-metestrous

*almost every day of the cycle has a large dominant sized follicle

Front 38

Equine estrous cycle
-periods

Back 38

-Estrus
-diestrus

*anestrus

Front 39

Equine anestrous
-occurs when

Back 39

-short days (fall, winter)

Front 40

Equine Estrus
-lasts how long

Back 40

-7 days

Front 41

Equine estrus
-presentation

Back 41

-mare receptive to stallion

Teasing
-interest in stallion
-urination
-vulva eversion
-squatting

Front 42

Equine estrus
-hormone levels

Back 42

-progesterone low
-estradiol high

Front 43

Equine estrus
-LH surge compared to other species

Back 43

-longer

Front 44

Equine estrus
-time of ovulation

Back 44

-24-48 hrs before end of estrus

Front 45

Equine estrus
-vaginal speculum exam

Back 45

-cervix swollen with relaxed folds hanging over the orifice
-large
-reddened
-edematous

*no cartilage unlike other spp

Front 46

Equine diestrous
-lasts how long

Back 46

-14-15 days (2 wks)

Front 47

Equine diestrus
-hormone levels

Back 47

-progesterone dominance (from CL)
-PGF2a secreted by day 13 if no recognition of pregnancy

Front 48

Equine diestrus
-presentation

Back 48

-mare refuses stallion

Teasing
-ears back
-biting
-kicking
-squealing

Front 49

Equine diestrus
-vaginal speculum exam

Back 49

-Os cervix tightly closed and surrounded by firm, well-defined folds

Front 50

Canine estrous cycle
-periods

Back 50

-anestrus
-proestrus
-estrus
-diestrus

Front 51

Canine Estrous Cycle
-what is interestrus

Back 51

-combination of diestrus and anestrus
-occurs 6 months of the year

Front 52

Canine estrous cycle
-LH surge most common to what animal

Back 52

-cow

Front 53

Canine estrous cycle
-how long does progesterone rise for

Back 53

-63 days

Front 54

Common method of determining estrous cycle stage

Back 54

-serial vaginal cytology
-collected with a cotton tip swab and stained with diff-quick

Front 55

Main effect of estrogen on vaginal cytology
-why

Back 55

Inc. estrogen
-vaginal lining thick causing dead cells
-b!tch is interested in mating causing the lining to thicken up and the surface cells to be located far from the blood supply

Dec. Estrogen
-vaginal lining is thin and cells are healthy
-B!itch isn't interested in mating so the vagina doesn't thicken and the surface cells stay close to the blood supply

Front 56

Parabasal cells
-morphology
-location

Back 56

-smallest, round to slight oval, large nuclei, little cytoplasm

-near the germinal cell layer, close to the blood supply

Front 57

Intermediate cells
-morphology
-representation

Back 57

-varied size, smooth oval to rounded irregular borders, small nuclei

-first step in cell death

Front 58

Superficial cells
-morphology

Back 58

-largest cells, sharp, flat, angular, small pyknotic nuclei

Front 59

Superficial-Intermediate cells
-morphology
-represent

Back 59

-healthy nuclei, angular, sharp

-estrogen effect on vaginal lining

Front 60

Anuclear squames
-morphology
-represent

Back 60

-dead, large, irregular, fully keratinized

-end of a process beginning with parabasal cells
-death due to thickened vaginal lining and movement from the blood supply

Front 61

Metestrum cells
-morphology
-seen when

Back 61

-large, intermediate with 1 or more neutrophils in the cytoplasm

-vaginal smear during early diestrus
-vaginitis

Front 62

Foam cells
--morphology
-associated with

Back 62

-parabasal and intermediate cells with cytoplasmic vacuoles

-diestrus & anestrus

Front 63

How long does interestrus need to last?

Back 63

>150 days

Front 64

Anestrus
-length of time

Back 64

-90-150 days post-whelping or post diestrus

Front 65

Anestrus
-necessary for

Back 65

-endometrial repair

Front 66

Anestrus
-presentation

Back 66

-no sexual interest from male or female
-normal looking vulva (no swelling or edema)
-basal progesterone levels

Front 67

Anestus termination
-hormone
-why should it not be done

Back 67

-prolactin

-the endometrium needs time to repair
-healthy litters won't be born if too soon

Front 68

Anestrus
-vaginal cytology

Back 68

-parabasal cells
-small intermediate epithelial cells
-neutrophils +/-
-NO RBCs
-Bacteria +/-

Front 69

Canine Proestrus
-length

Back 69

-5-10 days

Front 70

Canine Proestrus
-presentation

Back 70

-males interested in female
-female not interested in males
-swollen vulva due to estrogen secretion
-serosanguinous discharge resulting in diapedesis of RBCs through uterine vessels

Front 71

Canine proestrus
-most reliable clinical sign for onset of proestrus

Back 71

-first day of bloody vaginal discharge

Front 72

Canine proestrus
-hormone levels

Back 72

-LH has increased pulse frequency
-FSH suppressed
-Estrogen from growing follicles
-Testosterone high towards end (backing up of estrogen synthesis)

Front 73

Early proestrus
-vaginal cytology

Back 73

Similar to anestrus with varied amount of RBCs
-RBCs
-parabasal cells
-intermediate cells
-neutrophils common but not abundant
-some bacteria
-dirty background

Front 74

Mid-proestrus
-vaginal cytology

Back 74

-disappearance of neutrophils (estrogen effect)
-large intermediate and superficial intermediate cells
-+/- RBCs
-background dirty or clear

Front 75

Late Proestrus
-vaginal cytology

Back 75

-No neutrophils
-superficial cells with pyknotic nuclei or anuclear (dead cells)
-variable RBCs
-clear background

Front 76

Canine Estrus
-length

Back 76

-9 days

Front 77

Canine estrus
-presentation

Back 77

-male and female both interested
-b!tch will flag tail
-straw colored to pink vaginal discharge

Front 78

Canine estrus behavior
-result of

Back 78

-abrupt decline of estrogen

Front 79

Canine estrus
-hormone levels

Back 79

-dec. estrogen
-LH surge
progesterone secretion during mid-proestrus

Front 80

Effect of declining estrogen in canine estrus

Back 80

-b!tch goes from being passively resistant to breeding, to actively seeking
-strong positive feedback to the hypothalamus and pituitary resulting in a surge in secretion of FSH and LH at the beginning of standing heat

Front 81

Effect of LH surge on canine estrus

Back 81

-trigger for spontaneous ovulation
-ovulation about 2-3 days after LH surge
-ova released as primary oocytes and don't mature for 2-3 days

Front 82

How to determine the day of ovulation in a b!tch?

Back 82

-serial serum progesterone measurements

Front 83

Canine estrus
-vaginal cytology

Back 83

-no changes to suggest the day of LH peak or ovulation or the timing of fertilization

-superficial cells
-anuclear squames
- +/- RBCs

Front 84

Canine diestrus
-hormone levels

Back 84

Same in pregnant and non-pregnant b!tches
-progesterone dominance
-endogenous PGF2a not luteolytic
-exogenous PGF2a luteolytic as early as 5 days

Front 85

Canine diestrus
-presentation

Back 85

-female refuses male

Front 86

Covert pseudopregnancy
-define

Back 86

-diestrus in the non-pregnant b!tch due to progesterone remaining elevated even though there are no signs of pregnancy

Front 87

Diestrus
-length

Back 87

-60 days

Front 88

Canine diestrus
-vaginal cytology

Back 88

Clearly demarcated from the end of estrus
-number of superficial cells markedly decreases
-intermediate cells
-neutrophils reappear

Front 89

Why is knowing the beginning of diestrus important?

Back 89

-ovulation occurs 6 days before diestrus
-useful for prediction whelping time

Front 90

Feline estrous cycle
-periods

Back 90

-proestrus
-estrus
-metestrus

Front 91

Feline proestrus
-length

Back 91

-1 day or less

Front 92

Feline proestrus
-presentation

Back 92

-rejects male
-rolling, head rubbing, vocalizing, crouching

Front 93

Feline estrus
-length

Back 93

-6-7 days

Front 94

Feline estrus
-presentation

Back 94

-accepts male
-deviation of tail
-intensified rolling, head rubbing, vocalizing, crouching

Front 95

Feline estrous
-effect of being an induced ovulator

Back 95

-no LH surge without mating
-more mating = high and more prolonged LH release
-ovulation 50 hrs after LH peak

Front 96

Feline metestrus
-length

Back 96

-1-2 wks

Front 97

Feline metestrus
-effect of not being mated

Back 97

-LH not released
--no ovulation
---follicles regress (unique)
---progesterone does not rise above baseline (no ovulation)