SECTION 4: PERIODIC CHANGES OF ENDOME-TRIUM AND OTHER GENITAL ORGANS

1. Periodic changes of endometrium

Histological changes of endometrium:Endometrium includes function layer and basal layer. Function layer regenerates from the basal layer and desquamates in menstrual period. The periodic changes of endometrium are affected by ovarian hormones. For example, the normal menstrual cycle is 28 days. The periodic changes include three stages.

1.1 Proliferative phases （day 5 to day 14）: equivalent to the mature stage of follicle development, endometrial glands and mesenchymal cells show proliferative status under the effect of estrogen. It includes three periods: early, middle and late.

（1）Early period （days 5 to day 7）: the thickness of endometrium is only 2mm. The glandular epithelial cells are in cubic or low column shape; the stroma is dense and the cells are star-shaped; the small artery is straight and the wall is thin.

（2）Middle period （day 8 to day 10）: the glandular epithelial cells are columnar; the glands are increasing, elongate and slightly curve; interstitial edema is obvious; the spiral artery gradually develops and the wall becomes thick.

（3）Late period （day 11 to day 12）: the thickness of endometrium is 3 to 5mm and undulate-shaped. Epithelial cells present high columnar pseudostratified epithelium and karyok-inesis are increasing; the glands are longer and more curved; the stromal cells are stellate-shaped; tissue edema is obvious; the spiral artery slightly curved and the lumens expand.

1.2 Progestational stages （day 15 to day 28）:equivalent to the phase of the corpus luteum , the endometrium becomes thicker and presents secretory response; blood vessels increase rapidly and become more curved; interstitial edema is present. It includes three periods: early, middle and late.

（1）Early period （day 14 to 19）: The endometrium glands are longer and more curved; nuclear vacuoles are visible;interstitial edema is obvious; the spiral arteries continue to pro-liferate and curve.

（2）Middle period （day 20 to day 23）: The endometrium is thicker and serrated apocrine secretion++

（3）Late period （day 24 to day 28）:Before men-struation, the endometrium is 10mm and spongy-shaped. Endometrial glands are open to the uterine cavity, and excrete glycogen and other secretions, interstitial edema and loose, mesenchymal cells differentiate to decidual cells of hypertrophy. The spiral arteries become more curved and the lumens also expand.

1.3 Menstrual periods （day 1 to day 4）: the functional layer of the endometrium sloughs from the basal layer, forming the menstruation.

2. Periodic changes in other parts of the genitalia

2.1 Periodic changes of cervical mucus

（1）Characteristics: Before ovulation, the cervix rarely secretes mucus.. With the increasing concentration of estrogen,the secretion of cervical canals increases and becomes thin and transparent. This secretion can be drawn out to be more than 10cm during ovulation. The cervical external os appears like a pupil. “A fern leaf pattern” is seen as a result of crystal formation on a dried smear mad on a glass slide. This is most typical during ovulation. After ovulation, mucus secretion gradually decreases due to the influence of pregnancy hormone. Fern frond crystal completely disappears, forming the ellipsoid from days 22 days of the cycle.

（2）Clinical functions: Examination of the cervical mucus helps to monitor the function of the ovary.

2.2 Periodic changes in vaginal mucosa

（1）Characteristics: Vaginal epithelium is stratified squamous epithelium. Under the influence of estrogen before ovulation, the underlying cells of vaginal epithelial proliferate, gradually evolve into the middle and surface cells. Vaginal epithelium is thicker than before, surface cells keratinize, the degree of which is most obvious during ovulation.

（2）Clinical functions: These exfoliated cells can be scraped from the lower third of the vagina. By studying this idea regarding the concentration of estrogen in the body and whether ovulation has occurred or not can be made.

2.3 Periodic changes in oviduct

（1）Characteristics: During menstrual cycle, under the effect of estrogen, the changes of the morphology and function of the fallopian tubes are similar to endometrial changes, promote the development of fallopian tube and rhythmic contraction of the muscle layer. Progesterone can increase the rate of contraction of the fallopian tube, reduce the frequency of fallopian tube contraction, inhibit the growth of epithelial cells of the fallopian tube and reduce the function of the secretory cells.

（2）Effects: The synergistic effects of estrogen and pro-gesterone ensure the normal movement of the fertilized egg in the fallopian tube.

（王俊杰）