Researchers from the Stanford University School of Medicine and at UC-San Francisco have been able to separate stem cells from human testes which are capable of changing into other body tissues.

The researchers say that the quality of testes stem cells to change into other body tissues suggests that they bear a striking resemblance to embryonic stem cells.

They, however, caution against viewing them as one and the same.

The researchers revealed that the testes stem cells have different patterns of gene expression and regulation, and that they do not proliferate and differentiate as aggressively as human embryonic stem cells.

Their findings are in contrast to a previous study's that concluded that the cells were as pluripotent - meaning they can become any cell in the body - as embryonic stem cells.

''It's time to reinterpret the data, and to accept that we're beginning to discover many different types of stem cells. Although they are all related to each other, they also all have unique therapeutic applications in which they surpass other family members,'' said Renee Reijo-Pera, PhD, professor of obstetrics and gynecology at Stanford.

Working in collaboration with male infertility specialist Dr. Paul Turek, a professor of urology at UCSF and the director of The Turek Clinic in San Francisco, Reijo-Pera observed that the stem cells from the testes seemed to hover in a grey area between true pluripotency and the more limited, tissue-specific multipotency exhibited by many types of adult stem cells.