How to find the cortex in an ovary
It is generally where the follicles are hanging out. the boundary between cortex and medulla is indistinct.
Why do ovary cross sections look so different
Depends on stage of cycle, age of ovary, and species
Follicles consist of...
an oocyte, which is then encapsulated by one or more layers of cells.
The follicles that the woman is born with. All that she will ever have. Must migrate to cortex and be encapsulated or they will die before the woman is born. This process is not cyclical and not hormone-dependent. Consist of the oocyte with single layer of flattened follicular cells (these are the ones that must be present in order for the cell to survive). Primordial follicle that is encapsulated with follicular cells will be arrested in first meiotic division. Once they migrate to the cortex, they will be surrounded by stromal cells.
Progression from primary follicle to secondary follicle to Graffian follicle.
Form sexual maturity until menopause Hormone-dependent (GnRH)
Accumulate around the edge of primordial follicle after it migrates to the cortex; Become theca cells;
After the oocyte has been ovulated.
A primary oocyte within a primary follicle. Cells around the oocyte are now cuboidal and they're called granulosa cells. There is a now a basal lamina/membrane that separates granulosa cells from the stromal vasculature. So the oocyte is also separated., therefore the developing follicle is avascular and must depend on diffusion of nutrients from surrounding stromal cells. Next, the granulosa cells undergo multiple divisions to make multiple layers called the zona (stratum) granulosa. This is the first sign of follicular recruitment. Stromal cells differentiate into 2 layers: Theca intern (work w granulosa cells to prod estrogen) and Theca externa (will develop into smooth muscle cells that will help with ovulation of the oocyte later on). Zona pellucida develops between granulosa cells and oocyte. Helps send signals and nutrient to the oocyte.
When are the cyclical stages of follicle development?
Froms sexual maturity to menopause. Three phases: follicular, ovulation, luteal phase. Lasts 12-14 days.
- develops in the primary follicle between granulosa cells and oocyte. Helps send signals and nutrient to the oocyte. - key role in fertilization. Acrosome reaction when a sperm penetrates the oocyte membrane, resulting in spillage of proteases that crosslink with proteins in zona to trap sperm and close the barrier. --> prevents polyspermy, which is embryonic lethal
Development of the secondary follicle
- Antrum begins to form - fluid-filled cavity in a hole of lost granulosa cells, that is important for follicular growth, maturation, ovulation
Mature graafian follicle
Marked by the development of a full antrum, pushing oocyte off the one side of the follicle. The oocyte and surrounding zona pellucida and surrounding corona radiata cellsa will ovulate from the graafian follicle, leaving behind the corpus luteum.
the granulosa cells that are pushed the periphery of the graafian follicle by the antrum
granulosa cells dividing the antrum into a horseshoe and bridging the corona radiata and the zona granulosa
the granulosa cells between the oocyte and the antrum
theca interna cells
next to the granulosa cells and involved in hormone production
theca externa cells
smooth muscle cells that are important for assisting ovulation
What is ovulated from the graafian follicle?
oocyte + surrounding zona pellucida + corona radiata
what happens to the corpus luteum after ovulation?
the antrum fills with blood, which clots. Zona granulosa cells become granulosa lutein cells; theca interna cells become theca lutein cells - both of these now produce progesterone to maintain the uterine lining until implantation.
Potential fates of corpus luteum
1. Corpus luteum of pregnancy - if fertilization is successful. Enlarges. hCG from embryo tells corpus luteum to continue secreting progesterone (& estrogen). Becomes corpus albicans of pregnancy. 2. Corpus luteum of menstruation - pumps progesterone for about 12 days. Becomes the corpus albicans at end of cycle.
Estrogen secreted from follicle stimulates...
endometrial proliferation and at first inhibits FSH and LH.
Estrogen peak stimulates...
LH surge, which triggers ovulation.
corpus luteum changes hormone profile to produce....
progesterone. Estrogen is still there, but the progrestone is responsible for maintaining uterine lining and expansion of glands and arteries in the lining. It also suppresses LH and FSH.
Why is development of glands in the uterus important?
Glands produce glycogen. Glycogen is an early nutrient source for the implanting oocyte. There is not yet a placenta to get nutrients form mum.
What happens when progesterone rapidly drops
LH and FSH are not longer inhibited, endometrium is no longer maintained, and the endometrium sheds - new cycle begins.
Teal and orange arrows: what are they and what are their function?
Where is this slide taken from?
Teal arrows: Peg cells; produce nutrients to support the Graafian follicle. Nutrition provided is in addition to that provided by the corona radiata cells that were ovulated along with the oocyte.
Orange arrows: Ciliated cells; Cilia beat in unison to help move oocyte along oviduct
Taken from the ampulla of an oviduct. This is ciliated columnar epithelium studded with peg cells.
What layers are there in the ampulla of the oviduct?
Ciliated columnar epithelium
Smooth muscle (2 layers that are indistinguishable on histology)
What tissues form the placenta?
The villi and syncytiotrophoblast (contributed by fetus) and functional layer of maternal endometrium, which contributes lacunae containing maternal blood supply.
Identify A and B
A: maternal lacunae (in life this contains maternal blood, but not on histology)
B: Villus containing fetal blood
What three layers compose the maternal fetal diffusion barrier?
Endothelial cells of fetal blood vessels, connective tissue of villus, and syncytiotrophoblast cells interface with maternal blood.