Female Reproductive System

Ovaries Female gonads Attached to posterior surface of broad ligament by mesovarian ligament & attached to uterus by the ovarian ligament

Microscopic structure of ovary Surface covered by layer of germinal epithelium Within ovary, thousands of ovarian follicles which contain immature female sex cells, oocyte Primary follicles consist of oocyte surrounded by hormone secreting follicular or granulosa cells

Functions of the ovaries Produce female gametes or ova Oogenesis: process of egg production Ovulation: rupture of ovarian follicle & release of fluid & ovum Secrete female sex hormones, estrogen & progesterone

Uterine tubes or fallopian tubes or oviducts 10 cm long Attached to uterus at upper outer angles Lie in upper free margin of broad ligament Cup over but are not attached to ovaries

Walls of fallopian tubes Same 3 layers (mucous, smooth muscle & serosa) as uterus Mucosal lining is directly continuous with peritoneum lining pelvic cavity

Divisions of fallopian tubes 3 division –Isthmus: medial –Ampulla: intermediate dilated portion –Infundibulum: funnel shaped terminal part with fingerlike fimbriae

Histology of fallopian tubes Extensive folds in mucosal lining Cilia present on luminal surface important in maintaining currents to move ovum toward uterus

Function of fallopian tubes Ovum released from ovary are collected by fimbriae & swept along uterine tube toward uterus by cilia Site of fertilization

Uterus Pear shaped about 2 in by 3 in Two main parts: –Body: wide upper portion –Cervix: neck, lower narrow portion Bulging prominence above level of uterine tubes is the fundus

Walls of the uterus Endometrium Myometrium Perimetrium

Endometrium Inner layer composed of 3 layers –Stratum compactum: partially ciliated simple columnar epithelium, compact surface layer –Stratum spongiosum: spongy middle layer –Stratum basale: dense inner layer attached to underlying myometrium Compact & spongy layers slough during menstruation & delivery of baby Numerous exocrine glands: secrete mucus

Myometrium 3 layers of smooth muscle Thickest in fundus, thinnest at cervix

Perimetrium External layer, serous membrane Part of parietal peritoneum Covers none of cervix and part of body

Cavities of uterus Cavity of body is triangular with apex directed down: internal os, which opens into cervical canal Cervical canal is constricted at lower end forming the external os which opens into vagina

Blood supply of uterus Uterine arteries, branches of internal iliac artery Blood from ovarian artery & vaginal arteries reach uterus by anastomosis with uterine artery

Location of uterus Pelvic cavity between urinary bladder & rectum Age, pregnancy, bladder distension alter position of uterus At menopause uterus position drops in pelvis

Position of uterus Normally flexed over the superior surface of bladder Cervix pointing downward joining the vagina at approximately a right angle Fibers from several muscles form pelvic floor to form a node, perineal body which supports uterus

Eight uterine ligaments Three pairs, two singles hold uterus in position –Broad ligament (2): double folds of parietal peritoneum, uterus suspended between folds –Uterosacral ligaments (2) from posterior surface of uterus to sacrum –Posterior ligament: posterior surface to rectum –Anterior ligament: anterior surface to posterior surface of bladder –Round ligaments (2): cords extending from outer angles of uterus through the inguinal canal to labia majora

Functions of uterus Permits sperm to ascend toward uterine tubes If conception occurs –Embryo supplied with nutrients by endometrial glands until placenta produced –Placenta permits exchange of material between mother & fetus blood supplies but keeps two circulations separate –Myometrial contractions help push offspring out If no conception occurs outer layers of endometrium slough during menstruation

Vagina Tubular organ situated between rectum and urethra/bladder from cervix to vulva Collapsible tube capable of great distention, composed of smooth muscle with mucous membrane arranged in rugae Tiny exocrine glands secrete lubricating fluid for intercourse Anterior wall is shorter than posterior wall Hymen: fold of mucous membrane that forms a border around external opening of vagina

Functions of vagina Lining lubricates & stimulates penis during intercourse & thus acts as a receptacle for semen which often pools at fornix or corner of vagina Serves as lower portion of birth canal Transport of blood & tissue shed from lining of uterus

Vulva Female external genitalia Mons pubis: skin (hair) covered fat pad over symphysis pubis Labia majora: covered with pigmented skin & hair on outer surface, no hair on inner surface, homologous to scrotum Labia minora: medial to majora, covered with hairless skin. Area between labia minora is vestibule

More vulvar structures Clitoris: small organ of erectile tissue just behind junction of labia minora, homologous to corpora cavernosa & glans penis Urinary meatus: opening of urethra Vaginal orifice: located posterior to urinary meatus

Bartholin’s gland or greater vestibular gland 2 bean shaped glands on each side of vaginal orifice opens into space between hymen & labium minora, homologous to bulbourethral glands Also tiny mucous glands, lesser vestibular glands (Skene’s glands) open near urinary meatus

Functions of vulva Protective features of mons pubis & labia help prevent injury to clitoris & vestibule Clitoris becomes erect during arousal Vaginal orifice serves as a boundary between internal & external genitals

Breasts Lie over pectoral muscles attached by a layer of fascia Estrogen & progesterone control breast development during puberty –Estrogen: stimulates growth of ducts –Progesterone: stimulates actual secreting cells Size is more a function of fat than amount of glandular tissue

Structure of breasts Contain several lobes which contain several lobules which are composed of secreting cells (alveoli) arranged in grape like cluster Ducts from various lobules unite forming a single duct per lobe, ~ per breast which converge at nipple like spokes of wheel

More structure of breast Ducts enlarge before reaching nipple into lactiferous sinuses Nipples are bordered by a circular pigmented area, areola which contains sebaceous glands that appear as small nodules under skin which help reduce dryness associated with nursing Areola may darken as sign of pregnancy

Function of breast Lactation, secretion of milk for nourishment of newborns

Mechanism of Lactation Ovarian hormones act on breast to make them structurally ready Shedding of placenta, decreases estrogens which stimulates secretion of prolactin & oxytocin Prolactin: cause glands to secrete milk which starts 3 rd to 4 th day after delivery replacing colostrum Oxytocin: stimulates breasts to eject milk into ducts

Importance of Lactation Milk is source of protein, fat, calcium, vitamins Provides passive immunity in form of maternal antibodies present in colostrum Enhance maternal bond

Female Reproductive Cycles Menarche: onset of menses Menopause: cessation of menses

Ovarian cycle At birth ovaries contain many follicles with oocytes that has temporarily stopped meiosis On ~1 st day of menstrual cycle several follicles resume meiosis & follicular cells secrete estrogen Meiosis not completed unless fertilization occurs Ovulation: one of follicles migrates to surface & the wall ruptures releasing the ovum

Corpus luteum Ruptured follicle enlarges & is transformed into corpus luteum which grows for 7-8 days, secretes progesterone in increasing amounts If fertilization does not occur the corpus luteum decreases in size & secretions decrease eventually becoming white scar, corpus albicans

Menstrual cycle Variation in length of cycle After menstruation cells of endometrial layer proliferate & glands & vessels grow longer, coiled Endometrial glands secrete nutrient fluid between ovulation & next menses Day before menses begins, progesterone levels drop & walls of arterioles constrict causing ischemia & sloughing of tissue

Menstrual period (1 st phase) Occurs on ~days 1-5

Postmenstrual phase Also called preovulatory phase or follicular phase Between end of menses & ovulation Usually includes days 6-14 but considerable variation High estrogen level from developing follicle Proliferation of endometrial cells

Ovulation Often occurs on day 14 but varies

Premenstrual phase Also postovulatory phase or luteal phase Corpus luteum secreting progesterone Length of this phase fairly constant, usually 14 days

Control of Reproductive Cycles Increasing FSH: –Stimulates primary follicles & oocytes to grow –Stimulates follicular cells to secrete estrogen Level of estrogen gradually increasing during postmenstrual phase ten on ~12 th day leaps to a maximum peak LH surge then occurs 12 hours later which then triggers ovulation

Effects of LH Rupturing of mature follicle Formation of corpus luteum which then secretes progesterone

Control of cyclical changes in uterus Estrogen increases in postmenstrual phase –Proliferation of endometrial cells –Growth of endometrial glands –Increase in water content of endometrium –Increased myometrial contractions

Progesterone effects on uterus During premenstrual phase progesterone increases –Secretion by endometrial glands –Increase in water content of endometrium –Decreased myometrial contractions

If no pregnancy Low levels of FSH & LH cause regression of corpus luteum which causes drop in estrogen & progesterone which then triggers endometrial sloughing