Researchers at UC San Francisco have shown that a tiny population of cells in the brain, perhaps as few as 1,500, establish the basic rhythm of the reproductive cycle in humans. Researchers seeking to improve human fertility or birth control should thus focus on these cells, physiologist Richard I. Weiner said last week at a meeting of the Society for Neuroscience in St. Louis.
The cells are called GnRH-secreting neurons because they regularly produce gonadotropin-releasing hormone. The cells start the hormone cascade that ends in the release of a fertile egg from the ovaries and the production of fertile sperm. The start-up of this pulsed release in childhood stimulates the onset of puberty in both boys and girls.
Researchers have long debated whether the GnRH-secreting cells themselves originate the pulsed release, or whether other brain cells stimulate them to do so. Weiner and his colleagues devised a technique to isolate the cells from mice and grow them in a test tube.