What researchers are trying to do is unravel the mystery of the adult germ stem cells in male testicles, which are capable of producing an average of 1,500 sperm during every human heartbeat or an average of 130 million sperm a day.
"The average man will maintain a high level of sperm production from puberty onward, for decade after decade. To maintain that high a sperm output, you need many functioning stem cells. But the stem cells have to walk a tightrope and carefully balance the decision to become a sperm with the decision to stay a stem cell, so that the sperm output is maintained for all of these years," said Dr. Robert Braun, associate professor of genome sciences in the University of Washington School of Medicine.
The research was funded in part by the National Institute of Child Health and Human Development's Contraceptive Development Research Centers Program.
Stem cells are cells that are not differentiated that is, they have not acquired a particular type (such as lung cells, or blood cells). Researchers call stem cells 'pluripotent' cells, meaning that any given stem cell can become any of several types. In the early embryo, embryonic stem cells give rise to all of the cell types in the organism, including adult stem cells, which continually replace cells in the adult tissues that die or differentiate into more mature cells like red blood cells. In the adult testicles, the germ stem cells can produce more germ stem cells, but can also produce daughter cells that go on to become sperm. But resea
Contact: Walter Neary
University of Washington