Study Shows Estrogen-Testis Link

[Joy Towles <hope@igc.org>]

 Study Shows Estrogen-Testis Link



                                                           Updated 5:03
PM ET December 16, 1999

   By PAUL RECER, AP Science Writer

   WASHINGTON (AP) - Females in a laboratory-made mouse strain that
lacks key estrogen genes appear to
   develop normally, but then grow male testis cells in their ovaries,
researchers report.

   In a study appearing Friday in the journal Science, researchers in
North Carolina report they found that
   without a full complement of estrogen genes, cells in the adult mouse

ovary can switch to male-type cells.

   Researchers at the National Institute of Environmental Health in
Research Triangle Park, N.C., and at the
   University of North Carolina, Chapel Hill, made the discovery by
developing mice that lack the genes which
   causes estrogen, a natural female hormone, to send signals to cells.

   Mice with such deliberate mutations are called "knock outs" because
target genes have been removed, or
   "knocked out."

   The estrogen knock out mice survive to adulthood and appear normal,
but the animals are unable to reproduce,
   said J. F. Couse of the National Institute of Environmental Health
Sciences, the first author of the study.

   But microscopic studies of cells from the adult females show that
their ovaries begin to produce cells that are
   typically found in the male testis. The researchers said this is the
first documented sex reversal of cells in the
   adult ovary due to a disruption of the estrogen system.

   "Other researchers have produced male like cells in the mouse ovary,
but we are the first to do it by
   eliminating the estrogen genes," Couse said. "Also, the others did it

in fetal ovaries and we did it in adults."

   He said the knock out mice now can be used to better understand the
effect of estrogen on the growth and
   development of reproductive tissues in animals.

   Studying this subject is prompted, in part, because of concern that
some manmade chemicals in the
   environmental may possibly have an estrogen-like effect on some
animals.