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MBBS II ERS > L23 - Female reproductive cycle > Flashcards

L23 - Female reproductive cycle Flashcards

1
Q

List all the phases in prophase of meiosis?

A

–Preleptotene: DNA synthesis

–Leptotene: size increases; chromosomes visible

–Zygotene: pairing of chromosome at some points

–Pachytene: pairing along the entire chromosomes, shortening and thickening of chromosome; crossing over.

–Diplotene: formation of chiasmata(site of crossing over).

  • DICTYOTENE

–Diakinesis: shortening and thickening of chromosome

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2
Q

Primary oocytes arrest at which phase of Prophase I?

A

Dictyotene

before Diakinesis

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3
Q

Compare the separation of genetic material in Meiosis I and II?

A

–Meiosis I: separation of homologous chromosome

–Meiosis II: separation of sister chromatids

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4
Q

Define the 2 interruptions in the meiosis cycle of oocyte?

A

1st = At Prophase I (after dictyotene) until puberty

2nd = After metaphase II until fertilization

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5
Q

Define the number of oogonia formed in utero?

A

Increase to 7 million oogonia by 6 months (mitosis)

Degenerate to 1 million primary oocyte by birth

400 ovulated in life

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6
Q

5 MATURATION states** not folliculogenesis** of ovarian follicles?

A

Primordial follicle

> > developing follicle

> > mature follicle

> > ovulated follicle

> > corpus luteum

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7
Q

2 functions of ovarian follicles?

A
  • Reproduction: house the oocyte

* Endocrine: follicular cells respond to gonadotropins and sex hormones at different stages

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8
Q

Define the phases of folliculogenesis?

A

1) Follicular phase
2) Preantral phase
3) Antral phase
4) Preovulatory phase
5) Ovulation
6) Luteal phase

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9
Q

Describe the follicle maturation processes in follicular phase? think selection

A

High GnRH = high FSH/LH release at pituitary&raquo_space; FSH increase follicle growth

  • Recruitment: Cohort of prenatral follicles from resting pool grow (recruitment)
  • Selection: only 1 follicle develop into preovulatory follicle:
    Highest number of FSH receptor chosen
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10
Q

Describe the change in primary oocyte size in Preantral phase?

A

Primordial follicle: <50μm

|&raquo_space;> Primary follicle: 50-100μm

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11
Q

The preantral phase of folliculogenesis is gonadotrophin dependent. T or F?

A

False

not dependent
Able to respond to gonadotrophin at the end of Preantral phase

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12
Q

Describe the changes in the ovarian follicle during preantral phase?

A
  • Proliferation of follicular cells:
    a) Develop Zona Pellucida
    b) Develop Granulosa cells: express Estrogen and FSH receptor
    c) Develop Theca cell: express LH receptors
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13
Q

Role of granulosa cells in follicles?

A

Finger-like projections penetrate zona pellucida: allow external gonadotropin signal to go through to oocyte

> > regulate meiosis of oocyte

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14
Q

Describe the changes to ovarian follicle during antral phase of folliculogenesis?

A

Increase in size to 100-1000 μm

Secondary follicle formed:

Gonadotrophin dependent&raquo_space; Proliferation of follicular cells:

  • Formation of Antrum and Cumulus
  • Form Theca interna and externa
  • High FSH and Estrogen increase LH receptor expression at follicular cells
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15
Q

Explain the 2 cell theory of estrogen production? at thecal and granulosa cells

A

1) LH binds to LH receptor on thecal cells&raquo_space; convert cholesterol to androstenedione (androgen)&raquo_space; circulation or diffuse across basement membrane to granulosa cells
2) FSH binds to FSH-R on granulosa cells&raquo_space; stimulate aromatase to convert Androstenedione to estrogen&raquo_space; into circulation or follicular fluid

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16
Q

Explain how Antral phase follicular development is accelerated?

A

Estrogen simulate granulosa cells to increase cell division and express more estrogen receptors
» More estrogen made
» Positive feedback

17
Q

Describe the changes to follicle in the preovulatory phase of folliculogenesis?

A

Tertiary follicle formed: >1000μm

  • Increase size of antrum, stigma
  • Cumulus cells surround follicle > form corona radiata
  • LH surge completes meiosis-I , arrest at Metaphase II&raquo_space; secondary oocyte
  • Granulosa cells make low levels of Progesterone
18
Q

Describe the changes to ovarian follicle at ovulation? mechanisms to cause ovulation

A

Rupture follicle membran:

a) Increase production of follicular fluid&raquo_space; increase pressure in antrum
b) Produce Prostaglandin and proteolytic enzyme to dissolve follicular wall
c) Oxytocin contract follicular membrane

> > > Secondary oocyte and cumulus oophorus ovulated

19
Q

Describe changes to ovarian follicles at luteal phase?

A

Vascularization of the granulosa layer

Lutenization: Granulosa cell Hypertrophy + transform = Corpus luteum (80% granulosa cells + 20% thecal cells)

> > Production of estrogen, progesterone

20
Q

Compare the fate of the corpus luteum with or without fertilization?

A

Fertilization = Embryo blastocyst + placenta secrete hCG (LH-like) = maintain corpus luteum lifespan for 3 mon.

No fertilization: Luteolysis (degeneration) > corpus albicans

21
Q

List the hormones secreted by pituitary, hypothalamus and ovaries in female reporductive cycle?

A 
Hypothalamus = GnRH
Pituitary = FSH, LH
Ovary = estradiol, progesterone (feedback to hypothalamus)
22
Q

Summarize the role of estrogen from dominant follicle?

A
  • Primes endometrial response to progesterone
  • Primes GnRH action on LH secretion for LH surge
  • Enhances transport of ovum in oviduct
  • Enhances sperm transport through cervical mucus
  • Inhibits growth of cohort follicle
23
Q

Summarize the hormonal interaction during the follicular phase of folliculogenesis/ before ovulation? exam

A

GnRH stimulate synthesis and release of FSH and LH

> > FSH stimulate follicular development: Thecal, granulosa cells make Estrogen/Estradiol

> > Estrogen NEGATIVE feedback to pituitary and hypothalamus for GnRH and FSH, LH RELEASE

> > but stimulate pituitary for FSH, LH SYNTHESIS (store)

24
Q

Summarize the hormonal interaction during the Ovulation phase of folliculogenesis? exam

A

High estrogen for 2-3 days switches negative feedback to Positive feedback*****

  • Estrogen increase synthesis and RELEASE of FSH, LH

> > Cause FSH, LH surge

> > cause lutenization and form corpus luteum

> > Corpus luteum makes LOW progesterone and estrogen to positively increase GnRH release + Pituitary sensitivity

> > More FSH, LH released

25
Q

Summarize the hormonal interaction during the Luteal phase of folliculogenesis? exam

A

Switch from positive feedback to negative feedback:

  • HIGH estrogen and progesterone from corpus luteum decrease GnRH release
  • High progesterone block estrogen» block synthesis and secretion of FSH, LH
26
Q

Summarize the hormonal interaction during the end of Luteal phase of folliculogenesis without fertilization??

A

Corpus luteum luteolysis

> > decrease estrogen and progesterone release

> > Remove inhibition on GnRH

> > cycle restart

27
Q

3 functions of progesterone from corpus luteum?

A

 Control Ovulation
 Uterine secretion in preparation for implantation of the embryos
Development of the embryo

28
Q

Describe changes to cervical mucus in female sex cycle?

A

Before ovulation: Increase cervical mucus ‘ferning’ = decrease viscosity

After ovulation = no ferning = more viscous

29
Q

Changes in basal temperature during female sex cycle?

A

Decrease up to ovulation

Huge increase and plateau after ovulation

30
Q

2 phases of endometrium growth during female sex cycle?

A

Proliferative = follicular phase of ovarian cycle

Secretory = Luteal phase

31
Q

List 5 ways to detect ovulation?

A

Menstrual cycles–regular cycles

Basal body temperature

Urinary LH level

Blood-progesterone levels

Ultrasound

MBBS II ERS (37 decks)

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