Researchers from the National Institutes of Health and other institutions have identified in mice two proteins essential for ovulation to take place.
The finding has implications for treating infertility resulting from a failure of ovulation to occur as well as for developing new means to prevent pregnancy by preventing the release of the egg.
The proteins, called ERK1 and ERK2, appear to bring about the maturation and release of the egg.
The study, appearing in the May 15 issue of Science, was funded in part by two NIH institutes, the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) and the National Cancer Institute (NCI).
"Ovulation results from a complex interplay of chemical sequences," said Duane Alexander, M.D., director of the NICHD. "The researchers have identified a crucial biochemical intermediary controlling the release of the egg. The finding advances our understanding and may one day contribute to new treatments for infertility as well as new ways to prevent pregnancy from occurring."
The study's senior author, JoAnne Richards, Ph.D., of Baylor College of Medicine, worked with Esta Sterneck and Peter Johnson, of the NCI's Center for Cancer Research; with Heng-Yu Fan and Zhilin Liu of Baylor; Masayuki Shimada, of Hiroshima University, in Japan; and Stephen Hedrick, of the University of California, San Diego.
The immature egg is contained inside a covering of cells, known as the ovarian follicle. The follicle is made largely of cells known as granulosa cells. Each month, the pituitary gland releases follicle-stimulating hormone and luteinizing hormone which cause the egg and the ovarian granulosa cells surrounding it to grow and develop into a mature follicle. Midway through the woman's monthly cycle, the pituitary releases a large surge of luteinizing hormone, which causes the follicle to rupture, releasing the egg cell. The granulosa cells in
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NIH/National Institute of Child Health and Human Development