For the first time, scientists have found stem cells in the pituitary glands of mice that allow the organs to grow after birth.

The organ, which sits at the base of the brain and secretes hormones that regulate various bodily functions, had long been suspected as a source of stem cells, but this study represents the first time the hard-to-spot cells have been found there.

Neuroscientist Grigori Enikolopov, an associate professor at Cold Spring Harbor Laboratory, and his colleagues genetically engineered mice so that a certain gene expression, associated with neural stem cells, glowed green under ultraviolet light; almost 100 research teams worldwide have used these special mice to help locate adult stem cells in hair follicles, liver, muscle, and other tissues.

Now, as the paper "Genetic approaches identify adult pituitary stem cells" in the upcoming edition of the Proceedings of the National Academy of Sciences explains, the new research indicates that the adult pituitary includes two similar types of hormone-producing cells, which may allow the organ to respond differently to changing conditions.

In contrast to most adult stem cells, these pituitary cells are distinct from those that fuel the gland's initial growth. Researchers believe this is important because the hormone-secreting gland may adapt, even in adolescents and adults, to traumatic stress or to other life changes like pregnancy.