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