Female Reproductive Histology Flashcards
At birth, primary oocytes are arrested in what phase?
prophase of meiosis I
what happens to primary oocytes starting at puberty?
several begin to mature per month, although usually only one becomes fully mature and ovulates
When do oocytes become ova?
after fertilization, when they undergo the second round of meiosis
What is a follicle?
primary oocyte and its surrounding cells
What surrounds a primordial follicle?
a single layer of squamous cells. Until puberty, all follicles are primordial.
When does a primordial follicle become a growing follicle?
when follicle cells become cuboidal
At what stage in follicle development does the zona pellucida begin to form?
primary follicle
NOTE: Up to 20 follicles begin to develop during each menstrual cycle; only a few become secondary follicles.
What is the ZP secreted by and what is it rich in?
secreted by the oocyte and rich in glycoproteins
What happens to the follicle cells in the later primary follicle?
Follicle cells proliferate and stratify – now called granulosa cells; form stratum granulosum = membrana granulosa
In the later primary follicle, a basal lamina forms around the granulosa cells. What is it’s purpose?
basal lamina prevents blood vessels from growing into the follicle (from the stroma), but allows diffusion of hormones
When stratum granulosum is 6-12 cell layers thick (and the follicle is now called a secondary follicle), what happens?
fluid-filled cavities start appearing; these separate cavities eventually coalesce in one area, called the antrum, which gradually enlarges.
What does the follicular fluid inside the antrum of a secondary follicle contain?
hormones, growth factors & anti-clotting factors to help sustain the oocyte
In the graffian/mature follicle, how does the antrum appear?
horseshoe shaped
What do granulosa cells do in the mature graffian?
Some granulosa cells form a mound called cumulus oophorus
Other granulosa cells surround oocyte. The innermost of those granulosa cells stay with oocyte when it ovulates, forming corona radiata
After ovulation, the follicle (i.e. the remaining granulosa cells) becomes converted to what?
a corpus luteum
What eventually happens to the corpus luteum?
A corpus luteum eventually becomes converted to a pale scar called a corpus albicans
What are atretic follicles?
Of the ~20 primordial follicles that begin to develop during each menstrual cycle, usually one matures faster than the others and ovulates.
The others (19 follicles/month x 12 months/year x 40 years = 9120) undergo atresia (degeneration)
What happens to atretic primary follicles?
the oocyte and follicle cells die, are quickly resorbed, and stromal cells migrate into the area
What happens to atretic later primary and secondary follicles?
the follicle collapses, stromal cells migrate into the area, the oocyte degenerates and macrophages eventually phagocytose the dead oocyte & its zona pellucida.
But the granulosa cell basal lamina enlarges and forms a ‘glassy membrane’ that persists for some time*
What does the medulla of an ovary contain?
occupied by blood vessels, lymphatic vessels, and nerves
What does the cortex of an ovary contain?
contains ovarian follicles embedded in connective tissue
What kind of epithelium does an ovary contain?
simple squamous-cuboidal epithelium called ‘germinal epithelium’ covering the ovary
‘germinal’ is a misnomer; originally thought to be site of germ cell formation
What is contained in the cortex of an ovary?
1) germinal epithelium
2) tunica albuginea
3) follicles
4) CT with stromal cells and smooth muscle
As a follicle progresses from primordial to graffian, stream cells make layers around the developing follicle. What are these layers?
theca externa and theca interna
