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Reproduction > 2.7 The Oestrus Cycle Pt.1 > Flashcards

2.7 The Oestrus Cycle Pt.1 Flashcards

1
Q

What develops in the cortex?

A

the ovarian follicles

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2
Q

Medulla:

A

this is where the blood supply, nerves, and lymph goes to the ovaries

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3
Q

What is foliculogenesis?

A

The growth and development of ovarian follicles from the primordial follicle to ovulatory follicle stages of development​.

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4
Q

Foliculogensis stages

A

1) Primordial follicles
2) Growing follicles
- Early primary follicle
- Late primary follicle
- Secondary (antral) follicle
3) Mature (Graafian) follicles

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5
Q

primordial follicles:

A

pool of germ cells in females
- oocytes surrounded by layer of flattened granulose cells

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6
Q

Growing follicles: early primary follicle:

A
  • follicular cells are ​still unilaminar but now are cuboidal​ in appearance
  • oocyte begins to enlarge
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7
Q

Growing follicles: late primary follicle:

A
  • number of layers start to increase (multiaminar follicular layer), cells termed granulose cells
  • Formation of theca layer ( internal and external)
  • Zona pellucida layer : supports follicle and receptor for sperm during fertilization, gel like structure rich in gags

**Theca cells are vascularized
*Granulosa cells never vascularized

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8
Q

Growing follicle: secondary (antral) follicle:

A
  • cavities​ appear between granulosa cells forming an antrum
  • follicle continues to grow
  • formation of cumulus oophorus and corona radiata
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9
Q

Mature (Graafian) follicles:

A
  • Thecal cells outside; 2 layers external and internal
  • Granulosa cells inside
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10
Q

What fluid is located in the antral?

A

follicular fluid: contains hormones and nutrition to support​ the oocytes

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11
Q

The female mammal is born with a fixed number of?

A

follicles

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12
Q

At birth the ovary contains​ ?

A

all the follicles it is ever going to have

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13
Q

What is the functional​ unit of the ovary?

A

The follicle is the functional unit of the ovary containing both hormone-producing cells (granulosa and thecal) and a gamete (oocyte)

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14
Q

prior to ovulation where does oogenesis and hormone production occur?

A

in the follicle

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15
Q

the process of follicular growth?

A

folliculogenesis

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16
Q

What st​age do follicles begin?

A

Begin as primordial follicles which​ consist of one primary oocyte surrounded by a single layer of pre-granulosa cells

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17
Q

Development from the primordial follicles stage into the primary follicle is characterized​ by?

A
  • an increase in the size of the oocyte
  • surrounding of the oocyte by a single layer of cuboidal granulosa cells
  • and the separation of the oocyte from the granulosa cells by a thick layer of material, the Zona pellucida
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18
Q

Label the primary structure follicle:

A
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19
Q

The primary follicle will grow into?

A

a secondary follicle
- the granulosa cells proliferate into multiple layers and at the end of this stage the oocyte is fully grown

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20
Q

Events that characterize the secondary follicle are:

A
  • Theca layer which eventually will be oraginized into the interna and externa theca
  • vascularization of the theca
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21
Q

Atresia:

A

Not all follicles manage to reach the secondary follicle stage and can enter Artesia​:
type of cell death or degeneration
can happen via apoptosis or necrosis

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22
Q

Follicle growth part III:

A
  • connective tissue cells surrounding the granulosa cells differentiate to form layers of theca cells
  • despite the presence of the zona pellucida the inner granulosa layers are able to communicate with the oocyte gap junctions
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23
Q

Follicle growth pt 3: Theca cells produce?

A

androgens: act substrates for the synthesis of estrogens by the granulosa cells

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24
Q

Follicle growth pt. 3: granulosa cells secrete

A

Granulosa cells secrete:
- 17b- estradiol
- inhibin
- progesterone (small amounts)

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25
Label the secondary follicle:
26
Follicle growth​ IV:
Following the ​formation of the theca cells the primary oocyte reaches full size
27
Follicle growth​ IV: granulosa cells secrete
fluid resulting in the formation of a fluid-filled​ space called the antral follicle (tertiary follicle)
28
Follicle growth​ IV: Characteristics: of antral follicles are:
- development of gap junctions - differentiation of theca​ interna cells into steroidogenic cells
29
Follicle growth V:
- Antral follicels​ are responsive to gonadotrophins - mainly FSH
30
Follicle growth​ V: At the beginning of each cycle what begins to develop?
a few pre-antral follicles​ (primary follicles)
31
32
Follicle growth VI:
- further selection process occurs whereby a single follicle ( termed dominant follicle) is selected for continued development
33
Follicle growth VI: ___ will prevent complete antral development
Hypophysectomy
34
Follicle growth VI: For complete antral development ____ and ____ are needed?
LH and FSH
35
Follicle growth VI: The rest of the follicles with started ro​ enlarge undergo?
degenerative process termed atresia
36
Follicle growth VII:
- The dominant follicle enlarges, mainly as a result of its expanding antrum and its growth dependent on LH as the granulosa cells have now acquired LH receptors
37
Follicle growth VII: ____ will ​occur as a result of a dramatic increase in LH levels
ovulation
38
39
Horma=onal control of reproduction (list 3)
1. Hypothalmuns: Gonadotrophin -releasing hormone (GnRH) 2. Anterior pituitary: LH and FSH 3. Ovary: estrogen and progesterone
40
Ovarian cycles are termed either:
- estrous cycle: estrus is an easily identifiable external marker - menstrual cycle: menses is an easily recognized external marker
41
both estrus and menstrual cycles consist​ of what phases?
follicular phase and luteal phase
42
estrous cycle classifications: what are the 2 phases?
based on the changes in the cytology of the endometrium 1. proliferation phase: estrogen-dominant 2. secretory phase: progesterone​ dominant​
43
Follicular phase vs Luteal phase:
Follicular = short Luteal = longer period of time
44
Length of time between the 2 estrus cycles is called? how many days in this case?
estrus cycle = 21 days (cow)
45
end of 1st follicular phase =
a surge in LH, which causes ovulation *ovulation caused by corpus luteum
46
How can you determine that there is no pregancy by this graph?
Because of luteal lysis which means a new follicular phase begins
47
What causes the peak in E2 (estradiol) in this graph?
peak in E2 due to positive feedback
48
What causes P4 (progesterone​​) to increase in this graph?
ovulation
49
Why doe P4 eventually begin to decrease?
because the animal is not pregnant and the corpus luteum is starting​ to die
50
What hormone is produced when there is no pregnancy​?
PGF2 aplpha
51
Follicular phase summary:
- the period from the regression of the corpus luteum to ovulation - relatively short in length (20% of estrus cycle) - growth and maturation of ovulatory follicles - rise in blood estrogen, FSH, and LH concentrations - low concentrations of blood progesterone
52
Luteal phase
- period of regression until​ Corpus luteum regression - longer in length ( around 80%) - growth and maturation of the corpora lutea - rise in blood progesterone from CL, and relatively low FSH and LH concentrations
53
4 stages of estrus cycle:
1. pro-estrus: estrogen dominant 2. estrus: estrogen dominant​ 3. metoestrus: transitonal period 4. dioestrus: progesterone- dominant
54
proestrus:
- rapid follicle growth, FSH, and LH secretion - high estradiol secretion - rapid regression of CL and decrease in progesterone level
55
estrus:
- the female is receptive to the male and usually ovulates - estradiol is the dominant steroid hormone - LH surge causes ovulation and initiates corpus luteum formation - length of estrus varies: cow = 12hrs, mare 7-8 days
56
mestestrus:
- usually, 2-3 days long - CL forms - estrogen levels have decreased​ - formation of CL and increase in progesterone levels - metestrus​ bleeding
57
diestrus:
- Cl is fully functional, high progesterone - uterus​ is prepares to receive the developing embryo
58
What has to happen for the metestrus phase and diestrus phase to occur?
ovulation
59
what phase does ovulation occur after?
estrus phase
60
What is the dominant​ hormone is estrous phase?
estrogen
61
What is the dominant hormone in diestrus?
progesterone

Reproduction (15 decks)

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