The placenta secretes a number of hormones that affect the development of the breast. These are human Chorionic gonadotropins, estrogens, progesterone an human chorionic somatomammotropin.
Human chorionic gonadotropins (HCG) is a glycoprotein that contains galactose and hexosamine. It is produced by the syncytial trophoblast. HCG’s primary function is to prevent the normal involution of the corpus luteum at the end of the menstrual cycle.
Placental estrogen is synthesized from androgenic steroid compounds; dehydroepiandrosterone and 16-hydroxydehydroepiandrosterone, these weak androgens are transported by the blood to the placenta where they are converted to estradiol, estrone and estriol. The extreme quantities of estrogen cause the enlargement …show more content…
Progesterone causes decidual cells to develop in the uterine while also helping estrogen prepare the mother's breast for lactation.
Human Chorionic somatomammotropin (HCS) is secreted by the placenta at about 5 weeks of pregnancy. The amount of human chorionic somatomammotropin secreted increases as the weight of the placenta increases. Therefore low levels of HCS are a sign of placental …show more content…
The growth rate of the breast is further increased during pregnancy under the influence of estrogen secreted by the placenta. This second phase of growth causes the ductal system of the breast to grow and branch further. In addition, there is an increase in the amount of fat laid down in the stroma during pregnancy.
After the ductal system has developed, Progesterone then promotes the development and further budding of the lobules and alveoli of the breast. This results in the proliferation, enlargement and secretory nature of the alveolar cells. Progesterone also causes the breast to swell. Part of this swelling is due to the secretory development of the lobules and alveoli.
However, progesterone does not cause the alveolar to secrete milk. As much as estrogen and progesterone promote breast development and growth, they also inhibit the secretion of milk by the