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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
Q

Label the secondary follicle:

A
26
Q

Follicle growth​ IV:

A

Following the ​formation of the theca cells the primary oocyte reaches full size

27
Q

Follicle growth​ IV: granulosa cells secrete

A

fluid resulting in the formation of a fluid-filled​ space called the antral follicle (tertiary follicle)

28
Q

Follicle growth​ IV: Characteristics: of antral follicles are:

A
  • development of gap junctions
  • differentiation of theca​ interna cells into steroidogenic cells
29
Q

Follicle growth V:

A
  • Antral follicels​ are responsive to gonadotrophins - mainly FSH
30
Q

Follicle growth​ V: At the beginning of each cycle what begins to develop?

A

a few pre-antral follicles​ (primary follicles)

31
Q
A
32
Q

Follicle growth VI:

A
  • further selection process occurs whereby a single follicle ( termed dominant follicle) is selected for continued development
33
Q

Follicle growth VI: ___ will prevent complete antral development

A

Hypophysectomy

34
Q

Follicle growth VI: For complete antral development ____ and ____ are needed?

A

LH and FSH

35
Q

Follicle growth VI: The rest of the follicles with started ro​ enlarge undergo?

A

degenerative process termed atresia

36
Q

Follicle growth VII:

A
  • 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
Q

Follicle growth VII: ____ will ​occur as a result of a dramatic increase in LH levels

A

ovulation

38
Q
A
39
Q

Horma=onal control of reproduction (list 3)

A
  1. Hypothalmuns: Gonadotrophin -releasing hormone (GnRH)
  2. Anterior pituitary: LH and FSH
  3. Ovary: estrogen and progesterone
40
Q

Ovarian cycles are termed either:

A
  • estrous cycle: estrus is an easily identifiable external marker
  • menstrual cycle: menses is an easily recognized external marker
41
Q

both estrus and menstrual cycles consist​ of what phases?

A

follicular phase and luteal phase

42
Q

estrous cycle classifications: what are the 2 phases?

A

based on the changes in the cytology of the endometrium
1. proliferation phase: estrogen-dominant
2. secretory phase: progesterone​ dominant​

43
Q

Follicular phase vs Luteal phase:

A

Follicular = short
Luteal = longer period of time

44
Q

Length of time between the 2 estrus cycles is called? how many days in this case?

A

estrus cycle = 21 days (cow)

45
Q

end of 1st follicular phase =

A

a surge in LH, which causes ovulation
*ovulation caused by corpus luteum

46
Q

How can you determine that there is no pregancy by this graph?

A

Because of luteal lysis which means a new follicular phase begins

47
Q

What causes the peak in E2 (estradiol) in this graph?

A

peak in E2 due to positive feedback

48
Q

What causes P4 (progesterone​​) to increase in this graph?

A

ovulation

49
Q

Why doe P4 eventually begin to decrease?

A

because the animal is not pregnant and the corpus luteum is starting​ to die

50
Q

What hormone is produced when there is no pregnancy​?

A

PGF2 aplpha

51
Q

Follicular phase summary:

A
  • 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
Q

Luteal phase

A
  • 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
Q

4 stages of estrus cycle:

A
  1. pro-estrus: estrogen dominant
  2. estrus: estrogen dominant​
  3. metoestrus: transitonal period
  4. dioestrus: progesterone- dominant
54
Q

proestrus:

A
  • rapid follicle growth, FSH, and LH secretion
  • high estradiol secretion
  • rapid regression of CL and decrease in progesterone level
55
Q

estrus:

A
  • 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
Q

mestestrus:

A
  • usually, 2-3 days long
  • CL forms
  • estrogen levels have decreased​
  • formation of CL and increase in progesterone levels
  • metestrus​ bleeding
57
Q

diestrus:

A
  • Cl is fully functional, high progesterone
  • uterus​ is prepares to receive the developing embryo
58
Q

What has to happen for the metestrus phase and diestrus phase to occur?

A

ovulation

59
Q

what phase does ovulation occur after?

A

estrus phase

60
Q

What is the dominant​ hormone is estrous phase?

A

estrogen

61
Q

What is the dominant hormone in diestrus?

A

progesterone

Reproduction (15 decks)

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