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Reproduction > Oogensis and Estrous Cycle > Flashcards

Oogensis and Estrous Cycle Flashcards

(75 cards)

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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
What does seeing second polar body indicate?
That fertilization has occured
26
New dogma regarding oogenesis?
Females can renew their germ cell pool during adult life
27
A follicle is an oocyte surrounded by what?
somatic cells
28
Which follicles develop independently of gonadotropins?
Primary and secondary
29
FSH function
stimulates follicular growth
30
LH function
maturation of follicle | ovulation
31
What cells have FSH receptors?
Granulosa
32
What cells have LH receptors?
Thecal | later granulosa too
33
LH stimulates Thecal cells to produce what?
Androgen from cholesterol
34
FSH stimulates Granulosa cells to produce what?
Estrogen from androgen (from thecal cells)
35
Estrogen has what kind of feedbacks?
negative and positive
36
What is the only positive feedback in the body?
Estrogen causing LH surge
37
Low levels of estrogen vs. high levels
Low levels = negative feedback on gonadotropins | High levels = positive feedback on GnRH fo LH surge
38
LH surge unique in mares because
LH surge is not short lived like other species
39
Preovulatory Lutenization
Following LH surge, theca cells begin to produce low levels of progesterone
40
Does increased follicular pressure cause ovulation?
No, weakening of wall by thecal cells does
41
What do luteal cells form from?
Small luteal cells from Thecal cells | Large luteal cells from Granulosa
42
Formatuon of CL takes how long after ovulation?
5-6 days
43
What produces porstaglandin? What is the function of prostaglandin?
Endometrium of the uterus produces | PGF casues CL to regress
44
How does prostaglandin go from endometrium to the ovaries in ruminants?
Direct unilateral path using counter current diffusion
45
How does prostaglandin go from endometrium to the ovaries in the mare?
Goes through entire body (systemic pathway). Ovarian artery and uteroovarian vein are not close enough for diffusion.
46
Explain counter current diffusion of prostaglandin
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
Ovarian cycle
Oogenesis + Folliculogenesis
48
Define estrus
Heat: when the female is sexually receptive includes standing heat
49
Estrus vs. Estrous
``` Estrus = noun Estrous = adjective ```
50
3 types of estrous cycles
1. mono estorus 2. polyestorus 3. seasonally polyestrous
51
What species are considered monoestrus?
dog, wolves, foxes and bears | cycle once a year
52
What is non-seasonal polyestrus? What species have this?
Uniformly distributed estrous cycles throughout the year | Cow, Sow
53
What is seasonally polyestrus? Examples?
repeated cycles for a certain time of year and then a period of anestrous horses, sheep and goats
54
Diestrus vs. anestrus behavior? Which is more aggressive?
more aggresive during diestrus because of progesterone
55
Ovary activity during anestrus?
relatively inactive: no CL or follicles that ovulate
56
What can cause anestrus?
season, lactation, pregnancy?
57
What hormones are associated with estrus? Diestrus?
``` Estrus = estrogen Diestrus = progesterone ```
58
What is unique about first heat?
usually silent, no behavior
59
Day 0 of estrous cycle is what?
Day of ovulation usually
60
2 phases of estrous cycle? Percent of cycle and hormone present?
1. Follicular phase = 20% of estrous, estradiol | 2. Luteal phase = 80% of estrous, progesterone
61
Stages of estrous cycle in bovine? How many and what are they?
Proestrus (early follicular), Estrus (follicular), Metestrus (early luteal) and Diestrus (luteal)
62
Stages of estrous cycle in mare? What are they and how many?
Estrus and Diestrus
63
How long does it take CL to develop?
5 days (end of Metestrus/beginning of Diestrus)
64
Function of inhibin? What releases this?
Follicle releases inhibin to decreases FSH secretion
65
What hormone is species specific?
FSH
66
How are camelids and cats similar?
Induced ovulators
67
Progesterone has positive feed back on what 2 structures?
Endometrium (uterus tissue) for secretions | Mammary gland
68
Progesterone has negative feeback on what?
Hypothalmic GnRH and FSH and LH from anterior pituitary
69
What release prostaglandin?
Endometrium of the uterus
70
What increases melatonin?
More dark, lack of daylight
71
When do the doe and ewe cycle?
Cycle during fall and winter because short day breeders
72
When does the mare cycle?
Not during the fall and winter because long day breeder
73
Affect of decrease in daylight on doe and ewe? Mare?
Doe and Ewe: increase in melatonin increase GnRH | Mare: increase in melatonin decrease GnRH
74
Affect of increase in daylight on doe and ewe? Mare?
Doe and Ewe: decrease in meltonin decreases GnRH | Mare: decrease in melatonin increase GnRH
75
Define estrous cycle
Physiologic events that occur between successive periods of sexual receptivity

Reproduction (5 decks)

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