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Reproduction > Oogensis and Estrous Cycle > Flashcards

Oogensis and Estrous Cycle Flashcards

1
Q

Define Oogensis. What does oogenesis start with?

A

Formation of the female gamete. Starts with primordial germ cells

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2
Q

Primordial Germ Cells are haploid or diploid?

A

Diploid (2n) just like somatic cells

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3
Q

Oocyte are haploid or diploid?

A

Haploid (1n)

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4
Q

Zygote are haploid or diploid?

A

Diploid (2n)

Combination of oocyte and sperm

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5
Q

Result of mitosis?

A

diploid -> diploid

2 exact copies of diploid cells

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6
Q

Result of DNA synthesis on 2N2C?

A

2N4C, more chromatids

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7
Q

Result of meiosis?

A

Diploid -> haploid

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8
Q

Reduction occurs during what division in meiosis?

A

First division

2N4C -> (1N2C) X 2 [reduction] -> (1N1C) X 4

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9
Q

Prophase in meiosis vs. mitosis

A

Prophase is much longer during meiosis, years

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10
Q

Phases of mitosis and meiosis

A
  1. prophase
  2. metaphase
  3. anaphase
  4. telophase
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11
Q

Metaphase summary

A

homologs align equidistant to each other and form metaphase plate

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12
Q

Anaphase summary

A

homologs completely seperated from each other

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13
Q

Result of telophase 1st meiotic division

A

2 haploid daughter cells form as a result of reduction

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14
Q

Result of 2nd meiotic division

A

4 haploid daughter cells (1N2C) X 2 -> (1N1C) X 4

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15
Q

Meiosis summarized

A

2N2C -synthesis> 2N4C -reduction> 1N2C + 1N2C -2division> 1N1C + 1N1C + 1N1C + 1N1C

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16
Q

Once primordial germ cells reach gonadal ridge they become what in the female?

A

Oogonia interconnected by cytoplasmic bridges

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17
Q

How do oogonia multiply?

A

Mitosis

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18
Q

When does an oogonium (2N2C) become a primary oocyte (2N4C)?

A

After synthesis of DNA which is the initiation of meiosis

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19
Q

When is oogenesis arrested for the first time?

A

Dictyate stage of prophase prenatally and wait until adulthood

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20
Q

What activates oocyte after its first arrest during the Dictyate stage of Prophase?

A

Gonadotropin, specifically LH

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21
Q

What 3 things occur after LH activates the arrested Meiosis?

A
  1. Oocyte grows
  2. Zona pellucida forms
  3. oocyte becomes enclosed by primordial follicle
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22
Q

2nd meiotic arrest occurs when?

A

Metaphase II

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23
Q

What marks the end of the first meiotic division?

A

Extrusion of 1st polar body (1N2C)

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24
Q

What activates oocyte after second meiotic arrest?

A

Fertilization

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25
Q

What does seeing second polar body indicate?

A

That fertilization has occured

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26
Q

New dogma regarding oogenesis?

A

Females can renew their germ cell pool during adult life

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27
Q

A follicle is an oocyte surrounded by what?

A

somatic cells

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28
Q

Which follicles develop independently of gonadotropins?

A

Primary and secondary

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29
Q

FSH function

A

stimulates follicular growth

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30
Q

LH function

A

maturation of follicle

ovulation

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31
Q

What cells have FSH receptors?

A

Granulosa

32
Q

What cells have LH receptors?

A

Thecal

later granulosa too

33
Q

LH stimulates Thecal cells to produce what?

A

Androgen from cholesterol

34
Q

FSH stimulates Granulosa cells to produce what?

A

Estrogen from androgen (from thecal cells)

35
Q

Estrogen has what kind of feedbacks?

A

negative and positive

36
Q

What is the only positive feedback in the body?

A

Estrogen causing LH surge

37
Q

Low levels of estrogen vs. high levels

A

Low levels = negative feedback on gonadotropins

High levels = positive feedback on GnRH fo LH surge

38
Q

LH surge unique in mares because

A

LH surge is not short lived like other species

39
Q

Preovulatory Lutenization

A

Following LH surge, theca cells begin to produce low levels of progesterone

40
Q

Does increased follicular pressure cause ovulation?

A

No, weakening of wall by thecal cells does

41
Q

What do luteal cells form from?

A

Small luteal cells from Thecal cells

Large luteal cells from Granulosa

42
Q

Formatuon of CL takes how long after ovulation?

A

5-6 days

43
Q

What produces porstaglandin? What is the function of prostaglandin?

A

Endometrium of the uterus produces

PGF casues CL to regress

44
Q

How does prostaglandin go from endometrium to the ovaries in ruminants?

A

Direct unilateral path using counter current diffusion

45
Q

How does prostaglandin go from endometrium to the ovaries in the mare?

A

Goes through entire body (systemic pathway). Ovarian artery and uteroovarian vein are not close enough for diffusion.

46
Q

Explain counter current diffusion of prostaglandin

A

PGF leaves endometrium of the uterus via uteroovarian vein, ovarian artery sits right on top of this bringing blood to ovary/ PGF diffuses from vein to artery.

47
Q

Ovarian cycle

A

Oogenesis + Folliculogenesis

48
Q

Define estrus

A

Heat: when the female is sexually receptive includes standing heat

49
Q

Estrus vs. Estrous

A 
Estrus = noun 
Estrous = adjective
50
Q

3 types of estrous cycles

A
  1. mono estorus
  2. polyestorus
  3. seasonally polyestrous
51
Q

What species are considered monoestrus?

A

dog, wolves, foxes and bears

cycle once a year

52
Q

What is non-seasonal polyestrus? What species have this?

A

Uniformly distributed estrous cycles throughout the year

Cow, Sow

53
Q

What is seasonally polyestrus? Examples?

A

repeated cycles for a certain time of year and then a period of anestrous
horses, sheep and goats

54
Q

Diestrus vs. anestrus behavior? Which is more aggressive?

A

more aggresive during diestrus because of progesterone

55
Q

Ovary activity during anestrus?

A

relatively inactive: no CL or follicles that ovulate

56
Q

What can cause anestrus?

A

season, lactation, pregnancy?

57
Q

What hormones are associated with estrus? Diestrus?

A 
Estrus = estrogen
Diestrus = progesterone
58
Q

What is unique about first heat?

A

usually silent, no behavior

59
Q

Day 0 of estrous cycle is what?

A

Day of ovulation usually

60
Q

2 phases of estrous cycle? Percent of cycle and hormone present?

A
  1. Follicular phase = 20% of estrous, estradiol

2. Luteal phase = 80% of estrous, progesterone

61
Q

Stages of estrous cycle in bovine? How many and what are they?

A

Proestrus (early follicular), Estrus (follicular), Metestrus (early luteal) and Diestrus (luteal)

62
Q

Stages of estrous cycle in mare? What are they and how many?

A

Estrus and Diestrus

63
Q

How long does it take CL to develop?

A

5 days (end of Metestrus/beginning of Diestrus)

64
Q

Function of inhibin? What releases this?

A

Follicle releases inhibin to decreases FSH secretion

65
Q

What hormone is species specific?

A

FSH

66
Q

How are camelids and cats similar?

A

Induced ovulators

67
Q

Progesterone has positive feed back on what 2 structures?

A

Endometrium (uterus tissue) for secretions

Mammary gland

68
Q

Progesterone has negative feeback on what?

A

Hypothalmic GnRH and FSH and LH from anterior pituitary

69
Q

What release prostaglandin?

A

Endometrium of the uterus

70
Q

What increases melatonin?

A

More dark, lack of daylight

71
Q

When do the doe and ewe cycle?

A

Cycle during fall and winter because short day breeders

72
Q

When does the mare cycle?

A

Not during the fall and winter because long day breeder

73
Q

Affect of decrease in daylight on doe and ewe? Mare?

A

Doe and Ewe: increase in melatonin increase GnRH

Mare: increase in melatonin decrease GnRH

74
Q

Affect of increase in daylight on doe and ewe? Mare?

A

Doe and Ewe: decrease in meltonin decreases GnRH

Mare: decrease in melatonin increase GnRH

75
Q

Define estrous cycle

A

Physiologic events that occur between successive periods of sexual receptivity

Reproduction (5 decks)

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