Female histo Flashcards
Ovary histology
Surface epithelium - often missing from slides
Cortex: follicles are functional units
Medulla: boundary between cortices - indistinct
Non-cyclical follicular development
6th week embryonic: primordial germ cells (oogonia) migrate from yolk sac to gonadal primordia (presumptive ovarian cortex ) - mitosis
4/5 mo: > 7 million
Encapsulation by pre-granulosa cells and this arrest cell in first meiotid division. No oogonia in newborn.
Called primary oocytes in primordial follicles.
Primordial follicle recruitment into primary follicles start in fetal life and continues post-natally until ovarian reserve depleted
Gonadotropin INdependent
Primordial follicle structure
Very simple structures cytoplasm/organelles active nucleus with nucleolus flattened follicular cells surrounded by stromal cells
Non-cyclical primary follicle structure
still very simple structure
but cells surrounding oocyte are now cuboidal = granulosa cells
also: basal lamina separates granulosa cells and oocyte from stroma avsculature - developing follicles are avascular
Primary follicle (multi-laminar) structure
Granulosa cells have stratified = zona granulosum, 1st sign of follicular recruitment
Eosinophilic density forming around oocyte = zona pellucida
Granulosa cells send processes through zona pellucida to oocyte cytoplasm - gap junctions
follicle metabolically and electrically coupled
Theca folliculi on the outside of granulosa cells - interna/externa
Zona reaction
1) acrosomal reaction
2) rapid depolarization of oolemma
3) cortical granules fuse with oolemma
4) proteases in granules cross-link proteins in Z pellucia –> block further entry of sperm
Secondary follicle structure
1st sign of fluid-filled cavity = antrum
antral fluid has key role in follicular growht, oocyte maturation and ovulation
Formation poorl understood
but establizhes polarity and important regions of Graafian follicle
Graafian/Antral follicle structure
Zona granulosa on the periphery theca interna present cumulus oophorus Corona radiata and 10 oocyte theca externa = smooth muscle Follicle bulging under ovarian surface
Corpus luteum - fertilized ovum
corpus luteum of pregnancy
same organization, but enlarged
embryo - hCG-CL continues estrogen and progesterone secretion to maintain uterine wall
taken over by placenta at 8-12 wks
Corpus luteum - no fertilization
short lived
corpus albicans
Myometrium overview
outer muscular wall of uterus
thick sm wall
undergoes changes during pregnancy for fetus protection, expulsion
- increased E during pregnancy –> hyperplasia and hypertrophy of cells/increase in uterine collagen content
3 poorly defined layers
Uterine walls
myometrium
endometrium
outer serosa/adventitia depending on which part of uterus
Endometrium
mucous membrane comprising inner layer of uterine wall
Simple columnar epithelium and lamina propria, uterine glands, arteries
Mucosal lining that undergoes significant cyclical changes
Endometrial layers
Basal: adjacent to myometrium
closed tips of glands
largely unchanged throughout cycle
Functional: remainder of glands/epithelium
undergoes profound changes throughout monthly cycle
Menstrual phase endometrium
Only the base of glands remain
no epithelium - sloughed off
Straight arteries
Entire functional layer gone, only basal layer remains
Proliferative phase endometrium
Day 5-6: simple columnar epithelium regenerates
Remains unchanged until once again sloughed @ menstruation
Most endometrial CA are carcinomas, arising from epithelium that lines endometrium and forms the glands
Arteries of the uterus
Uterine artery –> 10 arcuate arteries –> radial arteries (penetrate myometrium)
Radial arteries of the uterus
Straight: supplies basal layer
Spiral: supplies functional layer
Glands of the uterus during proliferative phase
Early proliferative: at first sparse/straight
become coiled more closely packed during late proliferative phase
Glycogen synthesis begins (nutrition for fertilized ovum)
Secretory phase uterus
increased progesterone induces secretory changes in epithelium
still some ongoing proliferation due to estrogen
Arteries become increasingly tortuous
spiral in and out of section
Glandular changes during secretory phase
No change in epithelium
Saw tooth appearance in late secretory phase
Day 16: Basal vacuolation
Later: apical vacuolation
Implantation histology
hatched blastocyst “sticks” to endometrial epithelium - usually at embryonic pole
trophoblast quickly starts to proliferate/differentiates into 2 layers
Trophoblast differentiation
Syncytiotrophoblast - outer layer
- multi-nucleated protoplasmic mass without cell boundaries
- highly invasive: produces enzymes that erode maternal tissue
Cytotrophoblast - inner layer
important in chorionic villi growht during development of placenta
Development of the placenta
Cytotrophoblast proliferates to form primary chorionic villi = future fetal blood vessels
Syncytiotrophoblast breaks through maternal vessels - lacunae / vessels have direct contact
Intimate diffusion barrier but no mixing of blood
Placenta histology >5 mo
fetal/maternal interface: maternal blood in the lacunae
fetal blood in fetal vessels in the villi
Diffusion barrier between fetus and mother
Fetal blood Fetal endothelium Connective tissue (mesenchyme core) Syncytiotrophoblast Maternal blood (space = lacunae)
Histology/dating of the placenta
Trophoblast has 2 layers: cytotrophoblast/syncytiotrophoblast (formed from underlying cytotrophoblast)
1st part of pregnancy: 2 layers usually distinct on microscopic exam - date placenta/pregnancy
Fetal vessels with nucleated fetal RBCs appear at 21 d gestation
- presence of both trophoblast cell layers in absence of vessels –> pregnancy pregnancy 21 d - 5 mo
Histology/dating of the placenta >5 mo
After 5 mo: cytotrophoblast when viewed under a light microscope appears to degenerate
although cytotrophoblast has become thinner, remains throughout pregnancy, and all syncytial cells formed during latter half of pregnancy are formed from cytotrophoglast
Apparent absence of cytotrophoblast signifies a pregnancy > 5 mo
Histology/dating of the placenta toward term
Mesenchymal core of each villus becomes more dense and compact
fetal vessels appear to be much closer to overlying syncytiotrophoblast, possible facilitating transfer of nutrients or waste products
fibrin deposition within intervillous space and occasional syncytial knots
Fertilization timing
ovum has to be fertilized within 24-48 h
sperm appears in outer third of fallopian tube 5-10 min after coitus, continue to travel up for about 24-48 h
Fertilization place
usually at the ampulla of the Fallopian tube
Process of fertilization
1) sperm penetrates corona radiata with acrosomal enzymes
2) Bind and penetrate zona pellucida –> acrosomal reaction etc
3) once sperm penetrates ovum, ovum completes 2nd meiotic division
4) male + female pronuclei swell and form complete set of 46 chromosomes
5) 3-5 days post-fertilization for zygote to reach uterus while undergoing cell division
6) enters uterus as blastocyst; 1-3 days later, implants
