deck_699390 Flashcards
Ovaries Dual Function
Exocrine Gland – production of gametes• Cellular production: oocytes• Duct system: oviductEndocrine Organ – production of steroids• Estrogens (e.g. estradiol)• Growth of ovarian follicles and uterine lining• Breast development; 2ndary sex charcteristics• Progestins (e.g. progesterone)• Maturation of ovarian follicles, uterine lining, breast- aka – prepare internal organs for pregnancy
Ovary: general structure
Germinal epithelium Tunica Albuginea Cortex - Contains follicles in various stages of development • Stroma (inner cortex) • CT rich in cells and relatively poor in fibers - Modified fibrocytes and scattered smooth muscle cells - Associate w/ developing follicles; become specialized as thecal layersMedulla • Loose core of fibroelastic tissue • Abundant blood vessels • Nerve and lymphatic vessels
follicular development
Primordial follicle Early primary follicle Late Primary follicle Mature/Grafian follicleSecondary or antral follicle
Primordial follicle
oocyte (primary), surrounded by follicular cells (simple squamous), stromal cell on outer surface
Early primary follicle
oocyte grows and follicular cells become cuboidal; forming zona pellucida
Late Primary follicle
oocyte and granulosa layer separated by Zona pellucida, follicular cells proliferate to form stratum granulosa, stromal cells immediately surrounding follicle form Theca folliculi
Secondary or antral follicle
antrum formation begins - liquor folliculi amongst granulosa cells• Granulosa cells and oocyte form thickened mound into antrum -> cumulus oophorus• Cumulus oophorus cells surrounding oocyte = corona radiata• Theca layers differentiate, interna and externa - Interna – progesterone, highly vascularized - Externa – composed mostly of CT; aids motility -> smooth muscle cells
Mature/Grafian follicle
• Dramatic growth• Antral space gets much bigger• Granulosa cells become thin lining layerBasal lamina separating granulosa from theca interna becomes prominent • Theca interna – large spindle shaped cells w/ characteristics of steroid producing cells •Theca externa: collagenous fibers and fusiform cells
oocyte meiotic division
Primary oocyte – arrested for 12-15 yrs at meiotic prophase 1 -first meiotic division prior to ovulationSecondary oocyte – begins 2nd meiotic division as it leaves follicle, arrests at metaphase - Completes 2nd meiotic division upon penetration by spermatozoon
Ovulation
release of oocyte into ovary (day 14 b/w follicular and luteal phases)- Oocyte and corona radiata cells separate from granulosa cells and float free in follicular fluid- stroma thins, blood flow stops in a small area (stigma)- Wall is broken down (by proteolysis) and oocyte is released and caught by oviduct Fluid secreted by granulosa cells turger pressure wall rupture Theca externa smooth mm cells contraction aid release of oocyte
Corpus luteum
collapsed follicle undergoes reorganization into corpus luteum-> secretes progesterone
Corpus Luteum action in pregnancy
- Post fertilization increases in size- Secretes progesterone to block cyclic development of more ovarian follicles- Secretes relaxin – facilitates parturition- 6 months replaced by corpus albicans
Corpus Luteum Action in menstruation
In absence of fertilization and implantation, it degenerates in 10-12 days after ovulation• Replaced by white CT scar -> corpus albicans
Follicular Atresia
Degeneration of follicles (99.9%)Larger follicles: degeneration of Follical wall Smaller follicles: apoptosis of oocyte
Follicular phase
FSH acts on follicles -> estrogen production • Theca cells convert cholesterol -> androgen (LH activated) • Granulosa cells convert androgen -> estrogen (FSH activated)• Estrogen has + feedback on hypothalamic -> increase FSH secretion• Eventually estrogen levels reach point where has – effect on FSH and + effect on LH
Luteal phase:
LH increases and acts on corpus luteum -> Progesterone and estrogen secretion
Fallopian tubes
– muscular tube situated in edge of broad ligament – 4 segmentsInfundibulumAmpulla - site of fertilizationUterineIsthmus - more muscular
Oviducts/Fallopian tubes Function
-receives egg at ovulation and transports from ovary to uterus- Provides environment for fertilization
Oviducts/Fallopian tubes wall
thickens from infundibulum - isthmus3 layers: Mucosa: epithelium and lamina propria (Loose CT)• Epithelium – simple columnar• Lamina propria – loose connective tissue -> longitudinal folds 2 layers of smooth mm.• Some ciliated and some not Serosa (peritoneum) – mesothelium w/ thin CT layer
The oviducts: cyclic change
Follicular phase (estrogen) Increased ciliated/non-ciliated cells Increased cilia beating rateOvulation Fimbria closely opposed to ovarian surface Egg transported by cilia and peristalsis (3 day transit time)Luteal Phase (progesterone) Increased secretory/ciliated cells
The Uterus: parts
Body – expanded upper portion Site of implantationCervix – constricted inferior portion projects into vagina Endocervical canal • Os – constriction at each end of canal
Uterus wall
3 layers Endometrium (mucosa) Myometrium – muscular layer Perimetrium – uterine serosa
Uterus endometrium
Endometrium (mucosa) Simple columnar epithelium • ciliated cells and secretory cells • Uterine glands – simple tubular invaginations w/in stroma2 functionally different layers• Functional layer (stratum functionalis) inner layer (luminal side) • Sloughed off during menstruation resynthesized• Basal layer (stratum basale) outer layer
Uterus blood supply
• Uterine arteries – enter organ across myometrium• Arcuate arteries – • Radial branches – enter mucosa gives off straight arteries • Straight arteries – supply basal layer• Spiral arteries – give rise to lacunae supply functional layer • Distal portions lost during menstruation
Myometrium
3 ill defined layers – inner and outer longitudinal; middle circular or oblique Continuous w/ smooth muscle of oviducts and vagina Tremendous growth during pregnancy
Perimetrium
uterine serosa Layer of mesothelial cells supported by a thin layer of connective tissue Lower anterior surface adventitia instead of mesothelium
Endometrium and Myometrium cyclic changes each menstrual cycle
Menstrual phase: Day 1 – 4 -Entire functional layer sloughed offProliferative (follicular) phase: Days 4-13 (estrogen) - Epithelium restored - Stromal CT regeneration - Glands are straight with little secretory product - Blood vessels resynthesizedSecretory/Luteal phase: days 14-27 (progesterone) -endometrium growth -> due to Edema - glands enlarge and become corkscrew-shaped -> full of secretory product - Spiral arteries lengthen Ischemic phase: day 27-28 (removal of est & pro) • Glands stop secreting - Periodic contractions of smooth muscle -> ischemian -> necrosis -> necrotic functional layer removed
Pregnancy:
Ovum fertilized secretion of luteotropins by trophoblast of developing placenta to maintain corpus luteumPlacenta sustains progesterone secretion prevents ischemic changes that would normally lead to menstruation in an infertile cycle
Cervix
Mucosa - simple columnar epithelium• Changes to non-keratinized stratified squamous at portio vaginalis• Large branched mucus secreting glands (cervical glands)• Ovulation – secretory product of glands changes less viscous Muscularis – irregular bundles of smooth muscle in fibrous CT
Vagina
Mucosa stratified squamous non keratinized epithelium Lighter appearance due to glycogen storage Lamina propria – highly vascular w/ elastic tissue Numerous transverse foldsMuscularis – smooth muscle arranged in interlacing bundles Adventitia – thin inner dense CT (elastic fibers); outer loose CT
syncytiotrophoblast
Outer trophoblastic layer Invades epithelium and stroma of uterine endometrium bringing maternal blood close to placenta
cytotrophoblast
Inner trophoblastic layermitotically active
