Histology                                                                                                                     Stanley Shostak
BioSc 1450                                                                                                                  Spring 02

Lecture 21. Female Reproductive System

Ovary

ovarian cycle [Note: no oogonia in {most} adult mammals]; cohort of up to 20 primordial follicles [from each ovary] begins maturation; all but one undergo atresia; 40 oocytes x 12 = 480 per year x 40 (fecund) years = 19,200; follicle growth stimulated by FSH

estrus cycle: estrus vs diestrus; estrus vs menstrual

 germinal epithelium: mesothelium surrounding ovary
cortex: containing follicles, corpora albicantes, atretic follicles, corpora lutea.
stroma: tunica albuginea (white tunic): capsule of dense fibrous tissue; medulla:

Medulla:

highly vascular; ovarian artery and ovarian branches of uterine artery enter at hilum from broad ligament; ®helicine arteries; plexus at cortico-medullary junction ®straight cortical arterioles (radiate into cortex); form vascular arcades; give rise to capillaries around follicles; venous drainage same; lymphatics arise in perifollicular stroma; coil around medullary veins; sympathetic innervation terminate on smooth muscle of stroma around follicles;


cortex:

follicles: (source of follicular epithelium?); move into ovarian stroma during maturation and toward periphery at ovulation  
primordial follicles: contain primary oocyte (lg nucleus with dispersed finely granular chromatin, prominent nucleolus and little cytoplasm) surrounded by single layer flattened follicle cells

primary follicle

unilaminar primary follicle (FSH independent): contains primary oocyte (greatly enlarged) surrounded by a layer of cuboidal follicle cells

multilaminar primary follicle (FSH dependent = growing follicle): contains primary oocyte; zona pellucida secreted largely by oocyte; granulosa cells form zona granulosa = granulosa cells (named by von Baer before cell theory) surrounded by  basement membrane and stromal cells form theca folliculi


secondary follicles: zona granulosa (secretes intrafollicular FSH and produces estrogen from precursor produced by theca interna cells) grows; follicular antrum appears; oocyte reaches mature size; becomes situated in cumulus oophorus; theca folliculi differentiates into internal theca interna of rounded cells (epitheloid; features of steroid secreting cells; secrete estrogen precursors [androstenedione], of estrogen and progesterone) and theca externa (less well defined) of flattened stromal cells;

tertiary (Graafian follicles): 1.5÷2.5 cm in diameter; bulges below stigma; at approach to ovulation; primary oocyte completes 1st meiotic division and become secondary oocyte; cumulus oophorus diminishes to corona radiata; theca interna consists of plump steroid-secreting cells
 

 atretic follicles: Îatresiaâ refers to failure to perforate (i.e., ovulation) which leads subsequently to degeneration; zona pellucida Îloosensâ; oocyte degenerates (may divide); zona granulosa becomes disorganized; gross thickening of basement membrane = glassy membrane; replaced by ct.

corpora lutea (corpus luteum):

corpus luteum of menstruation (regresses 12÷14 days): zona granulosa cells ®granulosa lutein cells; lg, polygonal cells containing abundant pale eosinophilic cytoplasm and lg spherical nuclei with two prominent nucleoli; secrete primarily progesterone (and estrogen) under influence of LH; bright yellow pigment - lutein; cells of theca interna ®theca lutein cells smaller, more densely staining, less vacuolated cytoplasm, irregular ovoid nucleus with single large nuceolus; with finger-like extensions penetrating granuolosa continue to secrete primarily estrogens

corpus luteum of pregnancy (maintained initially by human chorionic gonadotrophin [HCG]; until the 12th week of pregnancy (placenta takes over secretion of estrogen and progesterone)
 

 corpora albicantes (corpus albicans): inactive fibrous tissue mass; acellular collagenous scar Genital tract: uterine tubes, uterus, vagin: wall of smooth muscle, an inner mucosal lining and an outer layer of loose supporting tissue;

Uterine tubes (oviducts or Fallopian tubes); movement of ovum (spermatozoa?) mediated by peristaltic action of longitudinal and circular smooth muscle; currents fluid propelled by ciliated epithelium; mucosa thrown into labyrinth of branching, longitudinal folds; branching core of vascular supporting tissue; single layer of tall columnar epithelium; two cell types: ciliated (more numerous) and nonciliated (taller [extend beyond ciliated cells]; produce secretion)

infundibulum: fimbriae extend from free edge;
ampulla site of fertilization
isthmus
interstitial part Uterus: shrinks to half former size after menopause
branches of uterine artery; pass through myometrium form 2 types:
straight (parietal) arteries: short, pass small distance into endometrium, bifurcate to form plexus supplying stratum basalis

spiral arteries: long, coiled and thick walled; pass to surface of endometrium; give off numerous branches; form capillary plexus around glands in stratum compactum; responsive to hormonal changes: constrict in response to witdrawal of progesterone; ischaemic phase preceeds menstruation

endometrium: mucosal lining; simple, tall columnar, some ciliated, microvilli epithelium folded into numerous, simple tubular glands;

stratum basalis: adjacent to myometrium; little changed during cycle

stratum functionalis

stratum spongiosum: broad intermediate layer; spongy stroma;

stratum compactum: superficial; compact stromal appearance; exhibit dramatic changes through cycle; shed during menstruationearly proliferative phase: proliferating glandular epithelium columnar cells with basally located nuclei; prominent nucleoli; highly cellular stroma devoid of collagen fibers

late proliferative phase: endometrium doubled in thickness; tubular glands become convoluted; plentiful mitocic figures; [note: mitotic figures Îabove crowdâ]; epithelium may have pseudostratified appearance

early secretory phase: glands irregular corkscrew; endometrium thickest; glycogen accumulates to form vacuoles in basal aspect of cells ® displacement nuclei higher = basal vacuolation

late secretory phase: saw-tooth appearance of glands containing copious thick-glycogen-rich secretions; cells pale, irregular and bloated with glycogen; mitotic figures absent; stroma maximally vascular; interstitial fluid begins to accumulate

at menstruation: spasmodic constriction of spiral arterioles; > ischaemia; degeneration superficial layers of endometrium; leakage of blood into stroma; degeneration of whole stratum functionalis; infiltrated by neutrophils; progressively shed as menses; does not glot due to release of local anticoagulant factors;

postmenopausal: reduced to former stratum basalis; glands sparse and inactive; may become dilated as cystic space filled with fluid; glandular epithelium cuboidal or near columnar; no mitotic figures or secretory activity; may be flattened; stroma much less cellular; no mitotic activity;

   myometrium: interlacing bundles of long fibers; ill-defined layers; rich network of arteries and veins supported by dense collagenous tissue; increases during pregnancy by hyperplasia and hypertrophy; becomes atrophic after menopause

uterine = menstrual cycle:

proliferative phase: begins on 1st day of menstrual cycle; ends at ovulation; initiated and sustained until ovulation by increasing production of estrogen; growth and development of numerous glands;

secretory phase: from ovulation to beginning of menstruation; endometrium glands begin copious thick glycogen-rich secretion coincident with ovultion; triggered by release of progesterone from corpus luteum after ovulation

 Cervix: mainly tough collagenous tissue containing relatively little smooth muscle; often inflitrated at os by leucocytes. endocervical canal: lined by single layer of (endocervical epithelium) tall columar mucus secreting cells; transists rapidly at external os, to stratified squamous epithelium;

ectocervix: stratified squamous epithelium [vaginal] ; clear cytoplasm, high glycogen content;

Îendocervical glandsâ = folds of surface; mucous secretory epithelium; secrete thin, watery mucus permitting passage of spermatozoa into uterus at ovulation; produce viscid mucus forming plug which inhibits entry of microorganisms from vagina following ovulation

 Placenta:

Vagina: fibromuscular canal; wall of mucosal layer lined by strtified squamous epithelium; dense lamina propria, with elastic fibers and rich plexus of small veins ; devoid of glands; layer smooth muscle and outer adventitia

vulva

labia

clitoris

 Breasts

revised: 04-05-01
last revised: 01-06-02