Unit 7 - Female Reproductive System I Flashcards
what is the hilus of the ovary?
conduit on anterior surface for blood vessels and nerves supplying ovary
how is the ovary suspended in the body?
ovary is suspended in perotoneal cavity by ovarian ligament (links ovary medial pole to uterus) and mesovarium (links ovarian hilus to broad ligament)
what are the 4 layers of the ovary, from outside in?
- germinal epithelium
- tunical albuginea
- cortex
- medulla
what is the germinal epithelium of the ovary? what is it continuous with? how is it related to ovulation?
simple, cuboidal epithelium
- continuous with mesothelium that lines mesovarium, broad ligament, and peritoneal cavity
- high regenerative capacity allows rapid healing after ovulation
what is the tunica albuginea? major cell type?
dense irregular CT
-rich in collagen (eosinophilic) and major cell type is fibroblasts (elongated nuclei)
what is the ovary cortex made of?
- follicles - oocytes plus follicular epithelium (in pre-menopausal only; grow bigger as they get closer to medulla)
- stroma - highly cellular CT with some smooth muscle
- endocrine glandular tissue sometimes
- some scattered smooth muscle cells
- low vascularity except around highly developed follicles and in glandular tissue
what is the ovary medulla made of?
loose connective tissue and blood/lymph vessels/nerves that enter at ovary hilus
what are ovarian follicle functions?
- house oocytes
2. make estrogen
what is the structure of ovarian follicles?
small spherical pockets
- follicular epithelium made of follicular cells surrounding a single, large oocyte in the center
- basement membrane of follicular epithelium defines outer boundary
- avascular, so oocyte depends on follicular cells for nutrient/waste management
oocyte formation
- primordial germ cells differentiate into oogonia
- oogonia proliferate via mitosis
- oogonia enter meiosis, and arrest in prophase I to stay as primary oocytes
follicle formation
- stromal cells around primary oocyte reorganize into follicular epithelium
- oocyte and follicle formation occur only during fetal development, although recent findings show oogonia persist in adult human ovary
- follicles are irreversibly lost through atresia or ovulation
primordial follicle information and histology
first follicle stage, and smallest type
- numerous in a fertile ovary, in dormant state maintained for decades
- central primary oocyte is very large, w/ eosinophilic cytoplasm, and decondensed nucleus
- -surrounded by simple squamous follicular epithelium (w/ low metabolic activity)
- apical follicular surfaces are tightly apposed to oocyte
- basal surfaces contact basal lamina surrounding follicle
follicular growth overview
oocytes grow in size (from 25 to 120 um)
- follicular epithelium grows in size
- fluid accumulates in follicle (antrum)
- stromal cells surrounding follicle reorganize and differentiate
- follicular growth culminates in ovulation
- at any point in the process, a follicle can undergo atresia
follicle activation
starts at beginning of menstrual cycle
- triggered by FSH activating primordial follicles
- follicular cells make aromatase to convert androstenedione to estrogen
- estrogen drives follicular cell mitosis
- only a subset of primordial follicles respond to FSH; most remain dormant
unilaminar primary follicle
second stage after primordial follicle
- primary oocyte grows rapidly; nucleus expands, organelles proliferate
- follicular cells proliferate to maintain epithelium around it, becoming simple cuboidal (increased metabolic activity)
- as follicles grow, they move deeper into cortex
multilaminar primary follicle
third stage, after unilaminar primary follicle
- oocyte continues to grow, and follicular cells continue to proliferate and make estrogen
- follicular epithelium becomes stratified cuboidal –> granulosa cells
- zona pellucida is secreted by primary oocyte
what is the zona pellucida made of and from?
thick, eosinophilic layer of glycoprotiens secreted by primary oocyte
-promotes sperm association and activation during fertilization
transport and signaling within multilaminar primary follicle
blood vessels don’t penetrate follicle, so all signals and nutrients must cross follicle basement membrane, granulosa, and ZP to reach primary oocyte
- filopodia from granulosa cells penetrate ZP to contact oocyte microvilli
- gap junctions between granulosa cells and oocyte facilitate transport and signaling across granulosa and ZP
secondary (antral) follicles
fourth stage, after multilaminar primary follicle
- granulosa cells continue to grow and make estrogen
- follicular liquid is secreted by granulosa cells, and when collected = antrum
- cumulus oophorous and corona radiata are present
what is the antrum made of?
follicular liquid secreted by granulosa cells
-rich in hyaluronic acid, steroids, steroid-binding PRO, and other substances
what is the cumulus oophorous? corona radiata? which stage of follicular growth are they found?
both in secondary (antral) follicles
CO: mound of granulosa cells that protrude into antrum
-surround and anchor oocyte to follicle wall
CR: granulosa cells of CO that contact zona pellucida
how is granulosa rearranged in secondary follicle?
with further follicular liquid accumulation in antrum, the oocyte and granulose cells are pushed to periphery
-along follicle’s surface, the granulosa has uniform thickness
mature (graafian or vesicular) follicle
usually, only one follicle becomes mature each menstrual cycle
-follicular liquid accumulation swells follicle to 2 cm diameter, becoming a “stigma” that bulges on the ovary surface
identifying features for:
- primordial follicle
- unilaminar primary follicle
- multilaminar primary follicle
- secondary follicle
- Graafian follicle
PF: central primary oocyte surrounded by simple squamous follicular epithelium
UPF: central primary follicle surrounded by simple cuboidal follicular epithelium
MPF: central primary oocyte surrounded by stratified cuboidal granulosa epithelium
SF: central or acentric primary oocyte surrounded by granulosa and 1+ antrum
GF: extremely large secondary follicle that bulges ovary surface outward
theca folliculi and components
stroma cells surrounding a growing follicle that differentiate to form the TF sheath; made up of 2 layers
- theca externa: supportive outer layer that provides structural support for follicle
- -smooth muscle cells, fibroblasts, and collagen fibers
- -blends with stroma
- theca interna: highly vascular inner layer with steroid hormone-producing (foamy) cells
- -foamy cells are pale and eosinophilic, have large, euchromatic nuclei, with extensive SER, mitochondria with tubular cristae
- -blood vessels of TI bring raw materials for hormone production, and carry hormone products away
atretic follicles
- when?
- what?
- small VS large atretic follicles?
programmed cell death can happen at any point during follicular development
- apoptosis of granulosa cells
- apoptosis and autolysis of oocyte
- destruction of ZP
- small (primordial follicles) vanish quickly
- large (secondary follicles) display dying granulosa cells with pyknotic nuclei (slough off into antrum), and macrophages invade follicle to clear debris
- in later stages, basement membrane thickens, and collapses into follicular space, leaving corpus fibrosum
what is the corpus fibrosum?
mostly acellular collagenous scar made in later stages of atresia, when basement membrane thickens and collapses into follicular space
what are interstitial glands?
when theca interna revert to regular stroma and retain hormone-producing character
- look similar to theca interna in cortex, but not associated with a follicle
- most commonly found during early puberty of humans, and in animals with large litters
transfer of oocyte to oviduct
ovulation expels oocyte complex into peritoneal cavity
- coagulation of follicular fluid holds oocyte complex on ovary surface
- finbriae cilia at mouth of oviduct guide oocyte complex into oviduct
oocyte complex
secondary oocyte + ZP + corona radiata (granulosa cells attached to ZP)
what happens hours prior to and immediately prior to ovulation?
hours before: primary oocyte completes meiosis I to make first polar body
immediately before: oocyte commences meiosis II and arrests at metaphase to make secondary oocyte
what happens to the secondary oocyte with and without fertilization?
with: finishes second meiotic division to make second polar body and mature ovum
without: secondary oocyte degenerates after 24 hours
what is the corpus luteum?
walls of ruptured follicle collapse into folds
- LH converts them into luteinized granulosa and theca cells
- -granulosa become steroid-producing cells
- -both cells undergo hypertrophy
- -massive thickening of collapsed wall makes CL large (2-3 cm)
- bleeding fills formur antrum with clot, and CT invades later
- since highly vascular, it allows import of raw materials and export of hormones
what are lipochrome pigments?
accumulate in luteinized granulosa cells to give ccorpus luteum its yellow collor
histology of luteinized granulosa cells VS luteinized theca cells
G: large, pale eosinophilic cells with foamy cytoplasm and large euchromatic nuclei
-prominent SER, alrge mitochondria with tubular cristae, and numerous lipid droplets
T: similar, but darker and smaller
where are luteinized granulosa VS theca cells?
G: make up bulk of corpus luteum
T: occupy outer contours of convoluted edges
what are CL hormone products?
progesterone and estrogen
fate of corpus luteum if no pregnancy
after 10-12 days, undergoes luteolysis
- corpus albicans is large CT scar that remains
- -dense collagen fibers make it large, mostly acellular, eosinophilic area
fate of corpus luteum with pregnancy
continued progesterone production is critical to maintaining pregnancy
how to tell the difference between corpus luteum and corpus albicans?
both are large, pale, and eosinophilic, but:
CL: highly cellular
CA: scar tissue is mostly collagen fibers with few cells
need higher mag to truly appreciate
