[To live or to die, an embryonic dilemma]

The development and formation of an organ needs both cell proliferation and cell death. It is commonly possible to decipher three types of basic cell death: 1) the so-called morphogenetic cell death (an example is the formation of the digits); 2) the histogenetic cell death like the apoptotic processes taking place in the spinal cord and allowing to regulate the number of motoneurons according to their targets; and 3) the phylogenetic cell death in which vestigial structures are selectively removed (e.g. destruction of the pronephros or removal of the tail in the anuran larva).