B8.025 The Ovary- Histology/Physiology Flashcards by Lauren Sinik

function of the ovary

to produce female germ cells, ova

to synthesize and secrete steroid and peptide hormones

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3 layers of the ovary

epithelium
cortex
medulla

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what is present in the cortex of the ovary

follicles containing oocytes at multiple stages of development
corpora lutea at various stages of function and regression

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what is present in the medulla of the ovary

vasculature
lymphatics
nerves

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ovarian surface epithelium

germinal

simple cuboidal: 1 layer, square in shape

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tunica albuginia

dense connective tissue

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what is folliculogenesis

the growth and development of immature follicles and oocytes to mature follicles and ova capable of undergoing ovulation and fertilization

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steps in folliculogenesis

primordial
primary
preantral
antral
Graafian

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description of structural components of primordial follicle

oocyte: “primary oocyte”, 25 um
squamous granulosa cells
basement membrane

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lifespan of primordial follicle

arrested in prophase of meosis 1
non-growing/resting pool go through rRNA, mRNA, and protein synthesis
eventually enter growing pool OR become atretic

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are primordial follicles dependent on LH and FSH?

NOOOO

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description of structural components of primary follicle

basement membrane
cuboidal granulosa cells (still 1 layer)
zona pellucida
growing oocyte in center

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changes in lifespan of primary follicle

enter growing pool

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what is the zona pellucida

composed of 4 glycoproteins (ZP1-4)
produced/secreted by the oocyte
transitional interaction between granulosa and oocyte

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function of zona pellucida

sperm binding receptor
acrosome reaction
block polyspermy
protection for embryo

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description of structural components of preantral follicle

theca differentiates
basement membrane
multiple layers of granulosa cells**

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function of basement membrane in preantral follicle

separates theca and granulosa cells

blood supply DOES NOT cross

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changes in lifespan of preantral follicles

granulosa cells proliferate
becomes able to respond to hormones
-theca : LH
-granulosa: FSH

description of new structural components of antral follicle

antrum forms, filled with follicular fluid
theca differentiates into interna and externa
granulosa continues to proliferate

how does the antrum form

first as several small pockets of fluid

eventually coalesces

changes in lifespan of antral follicle

increasing estradiol production

description of new structural components of Graafian follicle

granulosa continues to proliferate
increasing follicle diameter to 25 mm
increasing blood supply
oocyte pushed to one side

theca interna

large, round nuclei

steroidogenic cells

theca externa

fibroblast like cells

tether follicle to stroma of ovary

stimulation of ovulation

increasing estradiol | ovulatory surge of LH

what occurs in response to the ovulatory surge of LH

- BM breakdown - blood vessel penetration - oocyte moves to center of follicle - cumulus expansion - oocyte resumes meiosis - granulosa cell differentiation - enzyme production

oocyte resumption of meosis in ovaulation

completion of meiosis 1 first polar body formed oocyte arrests in metaphase II

granulosa cell differentiation in ovulation

aromatase off estradiol to progesterone proliferation stops

enzyme production in ovulation

``` histamine = hyperemia PA = breakdown of tunica albuginea ```

release of the oocyte in ovulation

increasing pressure proteolytic activity fimbrae and cilia beat and move oocyte into fallopian tube

formation of the corpus luteum

BM ruptures to allow vascularization of the antrum | granulosa and theca cells lutenize

lifespan of CL

predetermined no pregnancy > dies pregnancy > hCG maintains progesterone production

corpus albicans

remnants of a CL

what is atresia

degeneration/death of the follicle and oocyte

how does the oocyte complement develop

1. primordial germ cells migrate from yolk sac to gonadal ridge 2. oogonia undergo mitosis 3. oogonia enter meiosis 4. primary oocytes 5. arrest in prophase I of meiosis

initial organization of oocytes

initially in nests some undergo apoptosis remainder form individual oocytes with associated granulosa (primordial follicles)

regulation of primordial follicle formation

transcription factors, growth factors, meiotic proteins | CAV1, NGF, DMCI

discuss the finite number of oocytes

finite number established with development of the ovary at the start of puberty, constantly being recruited and entering the growing pool menopause occurs when the oocytes run out

biological checkpoint proteins involved in controlling female reproductive potential

``` bFGF KL BMP15 Foxl2 KGF AMH ```

3 phases of growth of the follicle

1. preantral (gonadotropin-independent) 2. tonic (gonadotropin-responsive) 3. exponential growth (gonadotropin-dependent)

preantral growth

gonadotropin-independent several months primordial follicle > primary follicle > preantral follicle

tonic growth

gonadotropin-responsive 2+ months early antral follicle > antral follicle

exponential growth

``` gonadotropin-dependent 21 days (portion of growth that is included in the menstrual cycle) Graafian follicle > ovulatory surge > ovulation ```