X-Message-Number: 23552
From: "Igor Artyuhov" <>
References: <>
Subject: Freeze-dried sperm can fertilize rabbit oocytes
Date: Thu, 4 Mar 2004 16:36:43 +0300

Source: EurekAlert
Public release date: 3-Mar-2004
http://www.eurekalert.org/pub_releases/2004-03/sfts-fsc030304.php

Contact: Dr. Xiangzhong Yang

Society for the Study of Reproduction

Freeze-dried sperm can fertilize rabbit oocytes

A team of reproductive biologists from the United States and Japan has
succeeded in fertilizing rabbit oocytes with "dead" freeze-dried rabbit
sperm. The fertilized eggs continued to develop into embryos, some of which
were transplanted into female rabbits.

The researchers---from the University of Connecticut, the University of
Hawaii, and Hirosaki University---note that rabbit sperm share many
similarities with human sperm, so their results suggest that the
freeze-drying technique could be used to preserve sperm from humans and many
other animal species.

Previously, only freeze-dried sperm from mice had been shown to support
embryo development. Mouse sperm, however, are significantly different from
sperm of most other mammals because they do not contribute a cellular
organelle known as a centrosome to the fertilized oocyte. The question
remains whether the centrosomes in rabbit sperm survive the freeze-drying or
whether centrosomes are not essential for embryos of mammals to develop.

Freeze-drying immobilizes rabbit sperm, breaks plasma membranes, and causes
fragmentation of the sperm tails. Nonetheless, the chromosomes remain intact
in the "dead" sperm. Even after being stored at temperatures above freezing
for more than two years, the treated sperm were as capable as fresh sperm at
fertilizing rabbit oocytes.

In a paper scheduled for publication in Biology of Reproduction, the team
headed by Xiangzhong Yang of the Center for Regenerative Biology at the
University of Connecticut, Storrs, and Ryuzo Yanagimachi of the University
of Hawaii Medical School, Honolulu, reports that one rabbit pup was born
after 230 oocytes fertilized with freeze-dried sperm were transferred to 8
female rabbits. The full-term pup appeared normal but was still-born, a
common outcome of single-birth pregnancies in rabbits.

The researchers believe that improvements in their procedure will someday
enable freeze-dried sperm of mammalian species to be stored indefinitely at
room temperatures.

###
Biology of Reproduction, published by the Society for the Study of
Reproduction, is the top-rated peer-reviewed journal in the field of
reproductive biology.

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