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
What Is This? What Is This? What Is This (known prior to 1980 as Anthym) was a rock band that originated in Fairfax High School in California and would play numerous shows along the coast of California. It was formed by guitarist Hillel Slovak, drummer Jack Irons, vocalist Alain Johannes, and bassist Todd Strassman. Originally named Chain Reaction, the band would later change its name to Anthem, then later to Anthym (as there was already a band using the former moniker), and then finally to What Is This, which was a tongue-in-cheek reference to the reaction they usually received from first-time listeners. During