What is the role of estrogen postimplantation?
Estrogen has a major role during pregnancy of building tissue. It accomplishes this by either increasing the size or the number of tissues, vessels, and blood cells.
- a major factor in the increased size of the uterus and thickening of the uterine wall (through hyperplasia (increase in the number of cells), hypertrophy (increase in the size of cells) of muscle cells, and stretching of the uterus) --> the uterus grows from 60 grams in weight to 1200 grams (20 times it's nonpregnant weight), with a volume increasing from 10 cc to 2-10 liters of fluid
- there is an increase in the size of the external genitalia; the vaginal walls are thick and easily distensible; the genitalia is also very vascular
- Estrogen is responsible for an increased blood, lymphatics and nerve supply to the uterus, and throughout the body
- Estrogen also contributes to the increase in breast size, especially the alveolar ductile tissue; the numbers and size of ducts and lobes increase, vascularity increases, and the nipples and areolae become larger
Another function of estrogen is change in the character of tissue:
- change in composition of the blood (increase in clotting factors, increase in leukocytes, increase in plasma volume (40-50%) and RBC count (20-30%)
- there is a softening of connective and collagen tissues; estrogen, along with the hormone relaxin, relaxes pelvic joints and ligaments
- estrogen is also responsible for skin changes (striae gravidarum, telangiectases, palmar erythema, hyperpigmentation)
- Estrogen also causes increased acidity (lower pH) in the vagina
- decrease in gastric secretion of hydrochloric acid and pepsin under the influence of estrogen
- increases uterine oxytocin receptors