In addition to deposition of fat, the formation of a duct system through which synthesized milk could pass through occurs. Estrogens also have a profound effect on the skeleton. It increases osteoblastic activity in that new bone is deposited over old. Osteoclasts have the function of removing old bone. If the rate of removal of old bone is greater than the deposition of new bone, thickening occurs.
Estrogens also cause early uniting of the epiphyses.
This results in the early cessation of growth observed in females in comparison to males. Another interesting fact about estrogen's effect on the skeleton is when the ovaries in older females that are in menopause secrete almost none of it. The result of this is diminished osteoblastic activity and decreased deposition of bone calcium and phosphate. The result of these two factors is osteoporosis. This form of osteoporosis is treated with estrogens.