Stem cell progeny tell their parents when to turn on

Stem cells switch off and on, sometimes dividing to produce progeny cells and sometimes resting. But scientists don't fully understand what causes the cells to toggle between active and quiet states. New research focused on stem cells in the hair follicle to determine what switches them on. The researchers found cells produced by the stem cells, progeny known at Transit-Amplifying Cells or TACs, emit a signal that tells quiet hair follicle stem cells to become active.