Actions of estrogen

I- On female sex organs:
1- The primary female sex organs (the ovaries):
a) It induces the growth and maturation of the graffian follicles.
b) It is essential for formation of the corpus luteum (by stimulating LH surge).
2- The secondary female sex organs:
a) Fallopian tubes: estrogen stimulates:
- Growth of its mucosal and muscular layers. - Its motility.
b) Uterus:
- It is responsible for the proliferative phase of the menstrual cycle.
- It stimulates growth of the myometrium, endometrial epithelium and glands.
- It increases uterine blood flow.
- It stimulates contractility of the myometrium.
- It increases sensitivity of the myometrium to the action of oxytocin.
c) Cervix: It makes the cervical mucus thin and alkaline which promotes the survival and
transport of sperms.
d) Vagina: It causes change of the vaginal epithelium into a stratified type which resists trauma.
II- On the female sex characters: estrogen is the feminizing hormone; it produces the following
changes in girls at puberty
a) Characteristic fat distribution: Fat is deposited in the breasts, lower abdomen, buttocks and
thighs (characteristic feminine contour).
b) Changes in the body configuration: Narrow shoulders & broad hips.
c) The skin is soft, smooth, more vascular and warm.
d) Feminine distribution of hair:
- Less body hair. - More scalp hair without frontal recession.
-The pubic hair is triangular with its base up.
e) The larynx and the vocal cords are not enlarged. So, the voice remains high pitched.
f) The breasts: It increases:
- The stromal tissues of breasts. - Development of the duct system.
- Fat deposition in the breast - blood flow of breast.
- Growth of the nipples and darkening of the areolas.
III- Psychological and behavioral changes:
Estrogens are also responsible for the psychological and behavioral changes that occur in girls at
puberty.
IV- General metabolic effects:
1- Anabolic effect on protein metabolism.
2-On bone:
a) It stimulates the osteoblastic activity.
b) It causes early union of the epiphysis so; the mature female is usually shorter than the
male.
3- It causes Na+ & water retention.
4- Cholesterol lowering effect