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Unit 1 ID+LC > Menstrual cycle > Flashcards

Menstrual cycle Flashcards

1
Q

What happens if the ovulated secondary oocyte is unfertilized?

A

it degenerates and is shed along with the stratum functionalis of the endomet.

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2
Q

Which germ cell is arrested in prophase I until the LH surge in ovulation?

A

Primary oocyte
- Diploid
- 2N, 4C
(46 sister chromatids are present)

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3
Q

After meiosis I, are the secondary oocytes diploid or haploid?

What else is produced after meiosis I occurs?

A

Haploid
1N, 2C

  • reduction in number of chromosomes from diploid complement (46 sister chromatids) to haploid complement (23 sister chromatids)

First polar body
*note that sec. oocyte contains majority of cytoplasm

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4
Q

The secondary oocyte is arrested in meiosis II until when?

A

It is completed only if fertilization occurs

- gives rise to ovum and second polar bodies

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5
Q

Difference between first and second polar body

A

first and second both contains 23 chromosomes (1N)

first: 23 chromosomes contain duplicated DNA (2C)
second: 23 chromosomes contain non-duplicated DNA (1C)
* technically the first polar body can degenerate or divide again

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6
Q

The terminology of Follicular phase and Luteal phase for the menstrual cycle is used in terms of what?

A

Ovarian fxn

  • luteal phase is most consistent in duration
  • formation of corpus luteum, regardless of fert
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7
Q

The terminology of the Mentrual phase, the Proliferative phase, and the Secretory phase for the menstrual cycle is used in terms of what?

A

Endometrial activity

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8
Q

Oocytes develop within a histologic unit known as the _____

A

ovarian follicle

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9
Q

Preantral and antral follicles consist of what during follicular development?

A

Preantral

  1. Primordial follicle
  2. Primary follicle
  3. Secondary follicle

Antral follicle

  1. antral follicle
  2. tertiary follicle
  3. graafian follicle
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10
Q

Do all follicles reach the antral stage each month?

A

no just 10-30 who happen to be in right place at right time.

But only 1 reaches dominance each cycle –> becomes antral fol –> ovulates

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11
Q

Once ovulation occurs, the resulting histologic unit in the ovary is the ________

A

corpus luteum

  • remaining shell of dominant follicle
  • one of the most vascular tissues in the body
  • this regression happens even if fertilization doesnt take place
  • no longer contains oocyte
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12
Q

Locally mediated autocrine and paracrine factors in follicular maturation

A

Inhibin: inhibits FSH (help dom fol)
Activin: augments FSH
Interleukin
Growth factors

*ie: VEGF is produced by granulosa cells in response to LH and induces angiogenesis in developing follicle

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13
Q

What aids to the more estrogenic microenvironment of the dominant follicle?

A
  1. Better blood supply
    - increases delivery of FSH to follicle
  2. More FSH receptors
  3. More granulosa cell proliferation
  4. More aromatase activity
    - more E production
  5. More Inhibin production from the dominant follicle
    - rising E and Inhibin [ ] exert (-) feedback on subsequent FSH secretion –> widening gap btwn itself and other non-dominant follicles in its cohort
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14
Q

When are primordial follicles completely formed?

A

6 months of life *frozen at prophase I

*only primordial follicle destined to ovulate becomes a primary follicle

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15
Q

What does the primordial follicle consist of?

A

primary oocyte

surrounded by layer of pregranulosa cells

surrounded by basement membrane

*most follicles remain in this state (prevent atresia of oocyte)

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16
Q

Only the primordial follicle destined to ovulate becomes a primary follicle. What does the primary follicle consist of?

A

Larger primary oocyte

  • surrounded by zona pellucida layer
  • facilitates sperm attachment to and fertilization of secondary oocyte

surrounded by single layer granulosa cells

surrounded by BM

*only thing thats new is ZP

17
Q

Secondary follicle consists of what?

A

primary oocyte

surrounded by ZP

  • surrounded by several layers of granulosa cells
  • they acquire receptors for FSH, androgens, and E, and become hormonally active

surrounded by bm

  • adjacent stromal tissue differentiates into theca cells
  • theca cells develop LH receptors and begin to synth. steroids.

*vascular supply to the area increases

18
Q

What change occurs in tertiary follicles (from secondary)?

A

FSH and estradiol cause the granulosa cells to proliferate + acquire LH receptors

  1. Antrum develops in granulosa
19
Q

What does antral fluid contain?

A 
estradiol
progesterone
androgens
inhibin
activin
FSH + LH
  • all play a role in follicular development, ovulation, and modulation of hormonal responses.
20
Q

Corona radiata

A

Seen in the secondary or Graafian or antral follicle

Inner layer of granulosa cells surround the oocyte
- starts becoming enveloped by antral fluid

*see image in handouts

21
Q

Cumulus oophorus

A

stalk that connects primary oocyte to remaining granulosa cells

*cumulus oophorus are located opp of the antrum

22
Q

Just prior to ovulation, the first meiotic division is completed, giving rise to secondary oocyte and first polar body.
What else occurs jsut prior to ovulation?

A

The cumulus oophorus breaks down and the oocyte, zona pellucida, and cumulus float within the enlarging follicle

  • the follicle ruptures during ovulation!
  • squish!
23
Q

What does the corpus luteum secrete?

A

estrogen and very high lvls of progesterone

- progesterone induces changes in the stratus functionalis which allows for successful implantation of fertilized ovum

24
Q

What happens to the corpus luteum and its progesterone secretion if fertilization occurs?

A

hCG secreted by conceptus maintains it for ~ 9 weeks until placenta is able to independently produce progesterone

*if fertilization does not occur, the CL regresses after 11 days

25
Q

What happens to the corpus luteum if fertilization does not occur?

A

*if fertilization does not occur, the CL regresses after 11 days –> reduction in progesterone –>
disintegration and sloughing of endometrial stratum functionalis –>
corpus luteum bcomes albicans (

26
Q

Pulsatile secretion of GnRH results in pulsatile release of LH and FSH. What inhibits LH pulses?

A

In the luteal phase, increasing progesterone lvls (from corpus luteum) will slow LH pulses.

27
Q

How does inhibin in the late follicular phase allow for the LH surge?

A

Inhibin enhances LH stimulation of the androgen synthesis in the theca
(providing more E synth in granulosa cell)

*inhibin also suppresses FSH secretion: ensures dominant follicle

28
Q

Estradiol is inhibitory at the level of hypothal and pit. at most [ ]s. When is this converted into a positive feedback mech?

A

High levels of estradiol (>200 pg/ml x 50 hours)
–> stimulates LH surge

*note that inhibin also stimulates LH surge by stimulating androgen synth in the theca

29
Q

Progesterone is inhibitory at _____ [ ]s, and stimulatory at _____ [ ]s.

A

high [ ]
(like after ovulation)

low [ ]s
(like before ovulation)
- progesterone facilitates the + feedback response of the pituitary to estradiol

30
Q

3 layers of endometrium

A
  1. stratum basalis
    - deepest layer immediately adjacent to myometrium
    - doesnt change much during menses

Stratum functionalis:
2. stratum spongiosum

  1. stratum compactum
31
Q

Permanent stromal tissue of endometrium and contains bases of endometrial glands

A

stratum basalis

32
Q

Straight vs spiral arteries of the endometrium

A

Straight arteries: feed stromal layer of endometrium, does not go deep

spiral arteries:

  • pass through basal layer into stratum functionalis
  • hormonally sensitive

Unit 1 ID+LC (32 decks)

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