Scientists find stem cells for the first time in the...( A team of researchers led by scienti...)

A team of researchers led by scientists at Cold Spring Harbor Laboratory have for the first time identified stem cells that allow the pituitary glands of mice to grow even after birth. They found that, in contrast to most adult stem cells, these cells are distinct from those that fuel the initial growth of this important organ. The results suggest a novel way that the hormone-secreting gland may adapt, even in adolescents and adults, to traumatic stress or to normal life changes like pregnancy.

Maturity, in some respects, brings diminished possibilities. As a fertilized egg cell repeatedly divides to grow into a mature animal, most of the resulting cells become ever more specialized. But a small number of cells, known as stem cells, remain uncommitted even as they spawn more specialized progeny. The most versatile stem cells, taken from days-old embryos, are able to form any cell type but studying them in people is controversial. Even in adults, however, other types of stem cell persist that have a more limited repertoire. Some replace specific cells as they wear out; others help to rebuild damaged tissues. Still other stem cells are suspected by some scientists of starting or maintaining cancers.

In spite of their importance, stem cells are hard to spot among the multitude of cells in complex tissue. Several years ago, neuroscientist Grigori Enikolopov, Ph.D., an associate professor at Cold Spring Harbor Laboratory (CSHL), and his colleagues developed a tool to look for stem cells that give rise to new adult brain cells. Researchers had known that a gene called Nestin was active in these neural stem cells. The CSHL team genetically engineered mice so that the same conditions that activate Nestin in a particular cell also make it glow green under ultraviolet light.

Using these mice gives researchers an important pointer to cells that may be adult stem cells. Almost 100 research teams around th
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