Overo refers to several genetically unrelated pinto coloration patterns of white-over-dark body markings in horses, and is a term used by the American Paint Horse Association to classify a set of pinto patterns that are not Tobiano.
Cerebrospinal fluid signals control the behavior of stem cells in the brain. FULL STORY. When stem cells from the old brain are cultured with signals of a young choroid plexus they can divide and form new neurons (red).
Control of Cell Division. Cell division usually limits itself, namely at certain checkpoints during the cell cycle. The majority of cells in the human body exist at the G0 stage of interphase, which denotes the state of nondividing cells. A cell will continue into the mitotic cycle if it receives a signal at the G1 checkpoint telling it to divide.