Female Reproduction II Flashcards
Oviduct subdivisions
- infundibulum- funnel shaped end where the oviduct lumen opens to the peritoneal cavity. Finger-like fimbriae surround the opening
- ampulla- longest portion, widest after the infundibulum
- isthmus- straight portion connecting the ampulla and uterus
- intramural part- passes through uterine wall
General Histology of Oviducts
- three layers: inner mucosa, middle muscularis, outer serosa
- no submucosa
Oviduct mucosa
-mucosal folds- fill much of the oviduct lumen. Most elaborate in ampulla simplest in the intramural part
-mucosal epithelium- simple, columnar epithelium, lines the oviduct lumen and surfaces of fimbrae two cell types:
+ciliated cells: pale eosinophilic cytoplasm, large euchromatic basal nucleus, prominent apical cilia and darkly staining basal bodies at the cilia bases. Function to sweep the oocyte complex or fertilized embryoes toward the uterus
+secretory cells: dark staining due to secretory products. Apical surfaces protrude above the epithelial surface, resembling pegs, hence also called peg cells. Function: their secretions nourish and protect gametes/embryos, and capacitate sperm activation
- lamina propria: highly cellular, well-vascularized CT. In the fimbriae, also contains smooth muscle to support fimbriae movements
- hormone sensitivity: estrogen stimulates cilia elongation, increased secretion by secretory cells, and hypertrophy of both epithelial cell types
Oviduct muscularis
- smooth muscle and some CT. Thick, inner, circularly-oriented layer and thin, outer, longitudinally-oriented layer. Thickens and becomes better defined from the infundibulum toward the uterus
- bends the infundibulum close to the ovary
- sweeps the fimbriae over the ovary surface
- peristaltic contractions propel fertilized embryos toward the uterus
Oviduct serosa
- well vascularized loose connective tissue
- simple squamous to cuboidal mesothelium covering
Ectopic pregnancy
- a fertilized embryo unable to reach the uterus may implant in the oviduct mucosa
- in absence of intervention or spontaneous termination: developing placenta erodes large blood vessels, growing embryo ultimately ruptures the oviduct, lethal hemorrhaging results
Anatomical overview of uterus
- upper uterine body, referred to hereafter simply as the uterus
- lower uterine cervix
- three histological layers: inner endometrium, middle myometrium, and outer perimetrium (or epimetrium)
Endometrium
- stroma- CT of amorphous group substance, some type II collagen, many fibroblasts
- surface epithelium: simple columnar epithelium that is only sometimes present
- uterine glands: simple, tubular glands lined by simple, columnar secretory cells. Continuous with the surface epithelium
- circulation:
- spiral arteries supply the upper endometrium (portion closest to the lumen), called the functional layer (functionalis)
- straight arteries supply the lower endometrium, called the basal layer (basalis)
- changes in ovarian hormones through the menstrual cycle cause loss and regrowth of the functional layer
- three recognized uterine phases: menstrual, proliferative, and secretory
Menstrual phase endometrium
- hormonal control:progesterone loss after luteolysis causes constriction of spiral arteries, hypoxia of functional layer. Straight arteries, and therefore the basal layer are not affected
- menstrual flow or menses: sloughing of the functional layer in response to tissue hypoxia
- thin endometrium, lacks a surface epithelium, very short glands
Proliferative phase endometrium
- hormonal control: estrogen produced by growing ovarian follicles acts as mitogen, promoting proliferation of stromal and gland cells
- surface epithelium regenerates from proliferating uterine gland secretory cells
- stroma thickens through replication of basal layer fibroblasts and production of extracellular material
- uterine glands lengthen
- spiral arteries grow into the reformed functional layer and sprout arterioles
- thick (2-3 mm) endometrium, numerous mitotic figures, particularly among the secretory cells, long,straight, narrow glands
Secretory phase endometrium
- hormonal control: progesterone from the corpus luteum stimulates secretory cell hypertrophy and secretory activity, and promotes vascular changes
- secretory cells hypertrophy: results in coiling of the uterine glands
- secretory cells secretory actvity: secrete glycogen-rich product through apocrine mechanism, glycoprotein-rich product through merocrine mechanism
- secretions: primary nutrition source for the embryo prior to and during implantation. Cause dilation of uterine glands
- thin-walled vascular lacunae develop and fill with blood. Provide abundant blood flow to the placenta in the event of implantation and pregnancy
- very thick (5-6 mm) endometrium, dilated coiled uterine glands, secretory product accumulated in secretory cells and gland lumens, prominent spiral arteries
Endometriosis
-presence of endometrial stromal and parenchymal cells outside the uterus
-endometrium sloughed during menses passes retrograde through the oviducts, into the peritoneal cavity
-potential sites: ovaries, outer surfaces of the oviduct or uterus, broad ligaments, colon, rectouterine pouch, and rectal sheath
Consequences
-endometrial tissue remains hormone sensitive, undergoing cycles of growth followed by bleeding through the menstrual cycle
-results in pain, inflammation, and the formation of adhesions between the organs and wall of the peritoneal cavity
-chocolate cyst- specific case of endometrial tissue invading the ovary tunica albuginea
Myometrium
- thickest layer of uterine wall
- bundles of smooth muscle are separated by connective tissue
- organized into three partially interwoven layers
Changes in myometrium during pregnancy
- hyperplasia (increase in cell number) of smooth muscle cells
- hypertrophy (increase in cell size) of smooth muscle cells
- increase collagen production by smooth muscle cells
- these changes thicken and strengthen the myometrium during pregnancy
- changes revert after pregnancy through smooth muscle cell apoptosis and/or atrophy and removal of excess collagen
Uterine leiomyomas
- fibroids
- benign smooth muscle tumors in the myometrium
- occur in one out of every four women