B8.025 The Ovary- Histology/Physiology Flashcards
function of the ovary
to produce female germ cells, ova
to synthesize and secrete steroid and peptide hormones
3 layers of the ovary
epithelium
cortex
medulla
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
what is present in the medulla of the ovary
vasculature
lymphatics
nerves
ovarian surface epithelium
germinal
simple cuboidal: 1 layer, square in shape
tunica albuginia
dense connective tissue
what is folliculogenesis
the growth and development of immature follicles and oocytes to mature follicles and ova capable of undergoing ovulation and fertilization
steps in folliculogenesis
primordial primary preantral antral Graafian
description of structural components of primordial follicle
oocyte: “primary oocyte”, 25 um
squamous granulosa cells
basement membrane
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
are primordial follicles dependent on LH and FSH?
NOOOO
description of structural components of primary follicle
basement membrane
cuboidal granulosa cells (still 1 layer)
zona pellucida
growing oocyte in center
changes in lifespan of primary follicle
enter growing pool
what is the zona pellucida
composed of 4 glycoproteins (ZP1-4)
produced/secreted by the oocyte
transitional interaction between granulosa and oocyte
function of zona pellucida
sperm binding receptor
acrosome reaction
block polyspermy
protection for embryo
description of structural components of preantral follicle
theca differentiates
basement membrane
multiple layers of granulosa cells**
function of basement membrane in preantral follicle
separates theca and granulosa cells
blood supply DOES NOT cross
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
- primordial germ cells migrate from yolk sac to gonadal ridge
- oogonia undergo mitosis
- oogonia enter meiosis
- primary oocytes
- 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
- preantral (gonadotropin-independent)
- tonic (gonadotropin-responsive)
- 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
