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
Giving Birth to a Stone in 2003. Bassist Justin Chancellor joined Tool in September 1995. Every song on "Giving Birth to a Stone" previously appeared on an earlier EP by the band. The songs "Signpost In the Sea," "Don't Make Me Your God" and "Dougal" originally appeared on the EP "Don't Make Me Your God", released in 1992.. The songs "Velvet" and "Peach" originally appeared on the EP "Disappear Here", also released in 1992. The songs "Burn," "Naked" and "You Lied" originally appeared on the EP "Burn", released in 1993. The songs "Spasm" and "Catfood" originally appeared on the album "Spasm", also released in 1993.