Mammary gland gestation, serum progesterone remains at a stably high concentration so signaling through its receptor is continuously activated. As one of the transcribed genes, Wnts secreted from mammary epithelial cells act paracrinely to induce more neighboring cells' branching. When the lactiferous duct tree is almost ready, "leaves" alveoli are differentiated from luminal epithelial cells and added at the end of each branch. In late pregnancy and for the first few days after giving birth, colostrum is secreted. Milk secretion (lactation) begins a few days later due to reduction in circulating progesterone and the presence of another important hormone prolactin, which mediates
The Marine Mammal Center The Marine Mammal Center The Marine Mammal Center is a private, non-profit U.S. organization that was established in 1975 for the purpose of rescuing, rehabilitating, and releasing, marine mammals who are injured, ill, or abandoned. It was founded in Sausalito, California by Lloyd Smalley, Pat Arrigoni, and Paul Maxwell. Since 1975 they rescued over 20,000 marine mammals. It also serves as a center for environmental research and education regarding marine mammals, namely cetaceans (whales and dolphins) and pinnipeds (seals, fur seals, and sea lions). Marine mammal abandonment refers to maternal separation; pups that have been separated from their mother before