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
March Mammal Madness to create a narrative to explain the loss. The narratives can range from a serious battle, to humorous happenstance. In 2014, research showed the pangolin to be the most trafficked animal on the planet. Before the match even began, the pangolin was captured by poachers and shipped away, forfeiting the fight. Each round has a scheduled day and time, found on Katie Hinde's blog, Mammals Suck... Milk!. Instead of just announcing the winners, the written narratives are live-tweeted like the match was happening that very moment. Fans can follow along and tweet back using the designated March Mammal Madness hashtag,