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Anatomy 2 > Lecture 22: Female cyclicity (Exam 2) > Flashcards

Lecture 22: Female cyclicity (Exam 2) Flashcards

(78 cards)

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1
Q

Define estrous

A

The length of the estrous cycle (in bovine its 21 D)

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2
Q

Define estrus

A

Period of sexual receptivity (heat)

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3
Q

Define Estrous cycle

A

Consists of a series of predictable reproductive events beginning @ estrus. Provides females w/ repeated opportunities to copulate & become pregnant

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4
Q

Define Anestrus

A

Not cycling

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5
Q

Define Estrual

A

Used to identify a condition related to estrus

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6
Q

Define parturition

A

Giving birth

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7
Q

Define Uterine involution

A

Acquisition of norm uterine size & fxn (gross & histologic have different time frames)

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8
Q

What are the types of estrous cycles

A
  • Polyestrus
  • Seasonally polyestrus
  • Monoestrus
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9
Q

Describe a polyestrus cycle

A
  • Have a uniform distribution of estrous cycles throughout the entire year
  • Cattle, Swine & rodents
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10
Q

Describe seasonally polyestrus

A
  • Have “clusters” of estrous cycles that occur only during a certain season of the year
  • Short day breeders: they cycle as the day length is decreasing (fall); sheep, goats, deer, & elk
  • Long-day breeders: they cycles as the day length increases (spring); mares
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11
Q

Describe monoestrus

A
  • Have only one cycle per year
  • Dogs, wolves, foxes, & bears
  • Domestic dogs typically have 3 estrous cycles per 2 years but are classified monoestrus
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12
Q

Label the types of estrous cycles

A
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13
Q

What are the two major phases of the estrous cycle

A
  • Follicular phase
  • Luteal phase
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14
Q

Describe the follicular phase

A
  • Primary ovarian structure is a large follicle(s)
  • Primary/dominant hormone = estradiol secreted by follicles
  • Period from CL regression to ovulation
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15
Q

Describe the luteal phase

A
  • Primary ovarian structure is the corpus luteum (CL)
  • The primary/dominant hormone = progesterone secreted by the CLs
  • Period from ovulation to CL regression
  • Follicles continue to grow/regress but do not produce high quantities of estradiol
  • 1 CL per egg
  • Twice as long as the follicular phase
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16
Q

What is the sequence of the estrous cycle

A

Follicular phase -> ovulation -> luteal phase -> follicular phase

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17
Q

Describe the levels of estrogen (E2) & progesterone (p4) during the estrous cycle

A
  • Begins to peak right before ovulation
  • Drops back down to the luteal phase
  • P4 goes down during the follicular phase w/ luteolysis then goes back up in the luteal phase
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18
Q

What are the 4 stages of the estrous cycle

A
  • Proestrus
  • Estrus
  • Metestrus
  • Diestrus
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19
Q

Describe proestrus

A
  • Begins whne progesterone declines as a result of luteolysis & ends @ onset of estrus
  • 2 - 5 D depending on species
  • Has major endocrine transition (P4 -> E2)
  • Pituitary gonadotropins, FSH & LH, are the primary hormones responsible for the transition
  • Antral follicles mature for ovulation & the tract prepares for estrus & mating
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20
Q

Which two stages are part of the follicular phase

A
  • Proestrus
  • Estrus
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21
Q

Describe the estrus stage

A
  • Peak of estradiol secretion by the dominant follicle
  • Female sexual receptivity
  • Visible behavioral symptoms so often the most recognizable stage
  • Duration varies
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22
Q

Which stages are part of the luteal phase

A
  • Metestrus
  • Diestrus
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23
Q

Describe Metestrus

A
  • CL formation (luteinization)
  • Beginning of progesterone secretion
  • Transition from estradiol dominance to progesterone dominance
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24
Q

Describe diestrus

A
  • Sustained secretion of high levels of progesterone from mature CLs
  • Longest stage of the estrous cycle (2/3 of the cycle)
  • Ends w/ luteolysis (destruction of the CL)
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25
label the image
26
Label the following
27
What are the exceptions to the estrous cycle
* The bitch * The queen
28
Describe the bitch estrous cycle
* Anestrus - 5 M; not ovulation * Proestrus - 9 D; start bleeding * Estrus - 9 D; start ovulating * Diestrus - 2 M
29
Describe the hormones during the bitch's estrous cycle
* FSH - Med to high (in anestrus or spayed); estrogen starts negatively feedback w/ FSH during proestrus * Estrogen - follicles grow & peak during proestrus then drops after estrus * LH - Has negative feedback w/ estrogen during proestrus so it drops * Ovulate & fertilize days after FSH drop * Progesterone increases during diestrus
30
Label the following:
31
Describe the queens estrous cycle
* Are induced ovulators * Proestrus * Estrus * Postestrus - Interestrus period in queen not mated (no ovulation); about 7 - 10 days * Only have diestrus if they were stimulated or had natural ovulation (about the same length as gestation) * Anestrus
32
Describe the hormones during a queen in estrus w/ no mate
* Estrogen is low w/ spikes * P4 stays low
33
Describe the hormones during a queen in estrus w/ a mate
* Still have spikes * High P4 during pregnancy * Dont have P4 during lactation so they can reproduce during lactation period
34
Label the following:
35
Describe anestrus
* "Without cyclicity" * Females that do not exhibit reg estrous cycles
36
What are the causes of anestrus
* Pregnancy * Lactation (not in cats) * Presence of offspring * Season (Photoperiod) * Stress * Pathology
37
What is true anestrus
* Insufficient hormonal stimulus * Due to poor nutrition, stress, pathology, high performing athletes b/c they don't have the energy to put into estrous
38
What is apparent anestrus
* Failure to detect estrus * Failure to recognize that a female is pregnant * Like a mare is at the bottom of the pack and doesn't want to show estrus
39
What is gestational anestrus
* Norm condition brought about by inhibition of GnRH by progesterone * Should ALWAYs be on dx list for anestrus * Owners sometimes have no clue about exposure & may even lie
40
What is lactational anestrus
* Not seen in cats * Not in mares, alpaca/llamas, & dairy cows * Lasts for variable amounts of time * Cyclicity is completely suppressed during lactation in the sow * Cyclicity can be delayed for as long as 60 D (suppression of LH)
41
what can influence the duration of lactational anestrus
* Suckling sessions (threshold not continuum) * 2 or less suckling sessions per day promotes return to cyclicity * 3 or more causes post partum anestrus * Dairy cows typically do not display lactational anestrus b/c the calf is removed * Beef cows typically have @ least a 60 D lactational anestrus
42
How does the presence of offspring affect cyclicity
* When calves are weaned suddenly from cows w/ intact mammary nerves the LH pulse freq & amplitude increases (cow returns to cyclicity) * Same thing happened when the nerves were cut * Suckling cannot be totally responsible for suppressing LH in the postpartum cow * Presence of the calf has some effect
43
What does seasonal anestrus enables animals to do
* Carry dev fetus during favorable time * Give birth during and advantageous time for new born
44
T/F: Seasonal anestrus can be modified by photoperiod to come back to cyclicity
True
45
What is the possible role of kisspeptin neurons in the regulation of cyclicity in long & short day breeders
* Long: More light = less melatonin = start cycling * Long day breeders: Increased kiss-10 causes increased GnRH which in turn causes increased FSH & LH * Short day breeders: Decreased Kiss-10 causes decreased GnRH which causes decreased FSH & LH
46
How does stress induce anestrus
* Neg energy balance * When an animal is starved the repro system is the first to shut down * Females consuming low quantities of E or protein often have sustained period * In lactating animals the lack of nutrition will prolong lactational anestrus (esp true for first time/young moms)
47
What is folliculogenesis
The process whereby immature follicles dev into more advanced follicles & become candidates for ovulation
48
T/F: Females make new eggs over time
False females are born w/ a few hundred thousand primordial follicles
49
What are the primary ovarian structures
* Primary follicles * Secondary follices * Antral (tertiary) follicle(s) * CL * Corpora albicans (a white scar(
50
What governs the follicular phase
* Hypothalamus * Anterior pituitary * Ovary through secretion of estradiol in the absence of progestrone
51
What are the four significant events of the follicular phase
* Gonadotropin (FSH & LH) released from the anterior love of the pituitary * Follicular preparation (growth) for ovulation * Sexual receptivity * Ovulation (LH)
52
What is the dominant hormone? What does it do?
* Dominant hormone: Estrogen * Causes changes in the reproductive tract * Behavioral changes * Controls the onset of preovulatory LH surge
53
What does the tonic center of the hypothalamus do
* Releases small amplitude pulses of GnRH that stimulate release of FSH and LH from the anterior pituitary * These cause the growth & dev of follicles on the ovaries * The follicles produce estrogen
54
What does the surge center of the hypothalamus do
* Responds in a positive feedback to the increasing levels of estrogen in the absence of progesterons * The positive feedback of estrogen on the hypothalamus causes release of a LARGE quantity of GnRH * This large dump of GnRH causes release of LH (LH surge) * Results in ovulation * The surge center is turned on once estrogen reaches a threshold level
55
Label the following steps leading to the preovulatory LH surge:
56
T/F: Estradiol exerts a positive feedback on the hypothalamus that drives the surge release of GnRH
True
57
Describe the hormonal profile of the follicular phase
* Declining progesterone (regression of the previous CL) * Increasing estrogen (growing follicles) * Increased FSH (recruits next wave of follicles) * Surge release of LH (low progesterone & high estrogen)
58
T/F: Follicles grow & regress constantly throughout the estrous cycle
True
59
Label the following
60
Describe the difference btw/ the types of follicles & oocyte
* Follicle is the sack that the oocyte is in * The secondary is bigger than the primary in both the follicle & oocyte
61
Label the following
62
What is recruitment (emergence)
Phase of follicular dev in which a cohort o small antral follicles begin to grow & secrete estrogen
63
What are the phases of follicular dev
* Recruitment (emergence) * Selection * Dominance * Atresia
64
Describe the recruitment
Phase of follicular dev in which a cohort of small antral follicles begin to grow (emerge) & secrete estrogen
65
Describe selection
* Follicles selected from prev recruited follicles * Either become atretic (die) or progress further * Follicles that progress continue to secrete increasing amounts of estrogen
66
Describe dominance
* Characterized by on (monotoccous sp) or more (polytocous sp) large preovulatory follicles * Follicles produce a large amt of estrogen & inhibin * The follicles undergo ovulation & the others die off
67
Describe atresia
* Antral follicles in when the antrum disappears (they die) * Most follicles that are recruited undergo atresia & very few advance to ovulation * Atresia occurs cont. throughout folliculogenesis
68
Define monotocous
Single follicle is selected
69
Define polytocous
multi follicles are selected
70
Where is the majority of a follicle's life spent
in the preantral stages
71
What % of follicles never ovulate (they undergo atresia)
> 99%
72
What are the hormones during recruitment
* High FSH * Low LH * No Inhibin * No estrogen
73
What are the hormones during selection
* Low FSH * Moderate LH * Low inhibin * Low to mod estrogen
74
What are the hormones during dominance
* Low FSH * High LH * High inhibin * High estrogen
75
What is the process of the 2-cell 2 gonadotropin model
1. When LH binds to theca cells it causes synthesis of enzymes that convert cholesterol to testosterone 2. When FSH binds to the granulosa cells it causes synthesis of enzymes that convert testosterone to estrogen 3. The estrogen leaches into the capillaries & become systemic 4. The systemic estrogen has effects on the brain of increased mating posture, phonation, & physical activity
76
How does system estrogen have an effect on the repro tract
* Increased BF * Edema of tissues * Secretion of mucus * Increased leukocytes * Increased smooth muscle motility * Growth of uterine glands
77
What is the steps of oogenesis
* Begins w/ the dev of primordial germ cells in the embryo * Primoridal cells divid e mitotically into oogonia * Oogonia divide into primary oocytes that enter the first meiotic prophase * At the end of the meiotic prophase the nuclear material is arrest (called dictyate) to form nuclear hibernation
78
What are the steps of oogenesis after puberty
1. The female begins to cycle & ovulate 2. The LH surge allows the meiotic arrest to be lifted & the first meiotic division takes place 3. This results in the formation of a secondary oocyte that possesses the first polar body (contains 1/2 of the genetic material that will be discarded. 4N to 2N) 4. Around the time of ovulation the second polar (2N to 1N) is voided & the ootid is formed 5. At fertilization the sperm delivers the other 1/2 of the genetic material & a zygote is formed 6. The zygote contains a male & female pronucleus when the pronucleii fuse early embryo dev begins

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