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Histo > Ovary, Hypothalamus/hypophysis > Flashcards

Ovary, Hypothalamus/hypophysis Flashcards

1
Q

Ovary functions

A
  • Production of oocytes
  • Production of hormones
    • Sex steroids - estradiol & progesterone
    • Protein hormones - relaxin, inhibin, activin
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2
Q

Ovarian cycle

A
  • Follicular phase (day1-14)
  • Ovulation (day 14-15)
  • Luteal phase (day 15-28)
    • Luteal regression begins ~day 24
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3
Q

How does follicle number change from birth to menopause?

A

You’re birthed with ~1 million primordial follicles, but you lose them through atresia nad through ovulation.

At menopause, you only have about 1000 primordial follicles, but they can’t develop –> loss of estrogens & progestins

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4
Q

What’s the average length of the ovarian cycle?

What is day 1 of the cycle represent?

What is menarche? What is menopause?

A

28 days

Day 1 of cycle = Day 1 of menses

Menarche: initiation of menses; ~12yo

Menopause: cessation of menses; ~50yo

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5
Q

Cycles vary from 21-35 days. What phase is the variation occuring in?

A

Follicular phase

Luteal phase is always 14 days

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6
Q

What happens in the follicular phase vs the luteal phase of the ovarian cycle? (general)

A
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7
Q

What happens in the ovarian cycle vs the uterine cycle?

A
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8
Q

What are the 4 stages of follicular development?

What are the cell types that make up follicles?

A

Primordial -> Primary -> Secondary (antral) -> Mature (Graafian)

Cell types: oocyte, granulosa cells, theca

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9
Q

What is the chromosome number of the oocyte in each follicular stage?

A

Primary oocyte (4N) until it meiosis makes it a secondary oocyte (2N) in the graafian follicle

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10
Q

Describe how the structure of the primordial follicle changes in maturation to the primary follicle

A
  • Primordial follicle (inner to outer)
    • ​Primary oocyte
    • > basement membrane
    • > follicular (squamous) cells
    • > stroma

Follicular cells become granulosa cells & zona pellucida forms

  • Primary follicle:
    • Primary oocyte
    • > zona pellucida
    • > granulosa cells (w gap junctions)
    • > basement membrane
    • > theca from fibroblast cells
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11
Q

What are the white bubbles at the edge of this ovary?

A

Primordial follicles

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12
Q

The majority of ovarian cancer arises from what cells?

A

The germinal epithelium at the cortex

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13
Q

What is the “PO”?

A

Primary oocyte

you can see how its wrapped by granulosa cells

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14
Q

What are the arrows pointing at?

A

At the edge by primordial follicles, so it’s germinal epithelium

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15
Q

Label these as primordial or primary follicles

A

Both are primary follicles because they have those granulosa cells and you can see the theca outside the basement membrane

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16
Q

Describe the structure of the secondary (antral) follicle

A
  • Inner to outer:
    • oocyte
    • zona pellucida
    • Granulosa cells & fluid-filled antrum
    • basement membrane
    • theca interna, theca externa - fibroblast-like cells differentiating into hormone-producing cells
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17
Q

What is this?

A

A secondary follicle because you can see the fluid filled antrum forming (white arrows)

TI= theca interna

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18
Q

Zona pellucida

A

gel-like, proteinrich layer secreted by oocyte

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19
Q

As the secondary (antral) follicle matures, what grows larger?

A

The antrum

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20
Q

Corona radiata

A

First layer of granulosa cells directly adjacent to the zona pellucida (mouse arrow).

  • Remains at ovulation
  • Sends cell processes through teh zona pellucida to communicate with the oocyte
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21
Q

What is the white arrow poitning to?

A

Basement membrane (usually stained a little pinker or darker red than this), but you know it’s between the granulosa and the theca

22
Q

Cumulus oophorus (CO)

A

all the granulosa cells that surround the oocyte, including that first layer - the corona radiata

23
Q

Structure of the mature Graafian follicle

Whats the difference between it and the secondary follicle histologically?

A

Very similar to the mature secondary follicle.

The only difference is its location - it’s gonna be closer to the edge because it was chosen to be ovulated

24
Q

Name the differentiation that occurs in follicle development

A

Squamous cells

–> Granulosa cells: secrete estrogens, has FSH receptors

Fibroblasts

–> theca interna: secrete androgens, has LH receptors

–> theca externa: fibrous & vascualr

25
Q

Follicular atresia

A

Happens to the majority of follicles; occurs via apoptosis

  • Starts during fetal life, continues a few years past menopause
  • Occurs at any stage during follicular development
26
Q

What does follicular atresia look like histologically?

A

The cumulus oophorus separates from the oocyte

Nuclei of granulosa cells look fucked up and squiggly

27
Q

Hormones involved in ovarian follicle development

A

GnRH (hypothalamus) goes to pituitary gonadotrophs

FSH & LH (pituitary) goes to granulosa & theca cell FSH & LH receptors to cause follicle development

Estradiol & inhibin B (ovary)

28
Q

Estrogen & progesterone-

Which one peaks before ovulation? Which one peaks after?

A
29
Q

Why can’t FSH ever be as high as LH?

A

It has inhibin suppressing it

30
Q

GnRH

Describe its path and its funciton

A
  1. Decapeptide synthesized by neuroendocrine cells whose cell bodies are in the arcuate & preoptic nuclei
  2. Released into primary capillary plexus in median eminence
  3. Hypothalamohypophysial portal system
  4. Pars distalis, where it binds GnRH receptors on gonadotrophs to synthesize and release FSH & LH

Fxn: pulsatile secretion in men and women causes puberty onset

31
Q

GnRH regulation during follicular phase

A

During the late follicular phase, positive feedback from estradiol –> increase the pulse frq of GnRH

32
Q

GnRH regulation during the luteal phase

A

Negative feedback from progesterone –> decrease GnRH pulse frq

33
Q

Other than estradiol (increase) and progesterone (decrease), what else influences GnRH pulse rate?

A
  • Stimulates: norepinephrine
  • Inhibits: dopamine, endorphins, melatonin, CRF
34
Q

What phase is the follicle in when estrogen reaches its peak?

What happens at peak estrogen?

A

Late secondary follicle- lots of granulosa cells producing estrogen

Low estrogen was negative feedbacking and suppressing GnRH, FSH, and LH.

But at these high levels, it then positive feedbacks and increases GnRH, FSH, & LH

35
Q

What is teh follicle in when progesterone reaches its peak?

What happens?

A

Progesterone is released from the corpus luteum

It negative feedbacks GnRH, FSH, and LH

36
Q

What causes the LH surge?

A

The peak of estradiol!

Estradiol positive feedback does not result in an FSH surge due to inhibin secreted by the granulosa cells suppresses FSH.

37
Q

Why doesnt estradiol positive feedback also result in an FSH surge?

A

Inhibin B secreted by granulosa cells selectively suppresses gonadotrophs secreted FSH

Targets pituitary and theca interna!

38
Q

What happens after the LH surge?

A

All that LH binds the LH receptors on theca cells

–> suppression of LH-induced synthesis of androgen precursors

–> no androgen precursors, so decreased estradiol synthesis.

39
Q

Do FSH & LH increase or decrease with age?

How do their relative proportions change in age?

A

Increase.

Reproductive period: more LH than FSH

Menopause: more FSH

40
Q

What kind of follicle is this

A

Squamous lining so it’s not granulosa cells - it’s a primordial follicle

41
Q

What are the light-staining cells surrounding the tip of the arrow?

A

granulosa lutein cells are paler

42
Q
A

Theca interna cells

Only way you can differentiate between theca interna & externa is just proximityt to the granulosa cells.

43
Q
A

Coiled glands -> secretory phase of uterus

Progesterone

44
Q
A

Primary oocyte

45
Q
A

Late (multilaminar) primary follicle

(no antrum, so its not secondary)

46
Q
A

Secretory phase because coiled glands

47
Q
A

external os

48
Q
A

Stratum granulosum

Cumulus oophorus is the granulosa cells connecting corona radiata to the rest of the granulosa cells; this is what will get degraded to release the oocyte

49
Q
A

Menstrual uterus - you can see the endometrium sloughing off

50
Q
A

B,D,A,C

A = epididymis due to stereocilia & smooth epithelial lining

B = seminiferous tubules in the testes

C = vas deferens due to 3 layers of smooth muscle

D = efferent ductules due to wavy epithelium

remember, SEVENUP

Histo (20 decks)

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