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
Mammal Species of the World In its Annual Report for 2015, the Committee noted that it is under contract with Johns Hopkins Press for the 4th edition of MSW, which will be edited by DeeAnn M. Reeder and Kristofer M. Helgen. The database has been made editable for the authors, leading to more frequent website updates. The publication was due in 2017. Mammal Species of the World Mammal Species of the World: A Taxonomic and Geographic Reference is a standard reference work in mammalogy giving descriptions and bibliographic data for the known species of mammals. It is now in its third edition, published in late