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
By Right of Birth By Right of Birth The film By Right of Birth premiered on June 22, 1921, in Los Angeles, California. This film is one of the few surviving films of the Lincoln Motion Picture Company, which is known as the first producer of race films and of such silent films as "By Right of Birth". The company was founded in 1916 and in 1923 produced its last movie, "The Heart of a Negro." The film was directed by Harry Gant, who is also responsible for the films "The Realization of a Negro's Ambition" (1916) and "Absent" (1928). The story was by