Simultaneous removal of sperm plasma membrane and acrosome before intracytoplasmic sperm injection improves oocyte activation/embryonic development
- *Institute for Biogenesis Research, University of Hawaii School of Medicine, Honolulu, HI 96822; and
- †Department of Physiology, Tokyo Women's Medical University School of Medicine, Shinjuku-ku, Tokyo 162-8666, Japan
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Contributed by Ryuzo Yanagimachi, September 21, 2006
Abstract
Direct injection of a single spermatozoon into an oocyte (ICSI) can produce apparently normal offspring. Although the production of normal offspring by ICSI has been successful in mice and humans, it has been less successful in many other species. The reason for this is not clear, but could be, in part, due to inconsistent activation of oocytes because of delayed disintegration of sperm plasma membrane within oocytes and incorporation of the acrosome containing a spectrum of hydrolyzing enzymes. In the mouse, the removal of sperm plasma membrane and acrosome was not a prerequisite to produce offspring by ICSI, but it resulted in earlier onset of oocyte activation and better embryonic development. The best result was obtained when spermatozoa were demembranated individually immediately before ICSI by using lysolecithin, a hydrolysis product of membrane phospholipids.
Footnotes
- ‡To whom correspondence should be addressed. E-mail: yana{at}hawaii.edu
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Author contributions: K.M. and R.Y. designed research; K.M. and T.S. performed research; T.S. and S.M. contributed new reagents/analytic tools; K.M., T.S., S.M., and R.Y. analyzed data; and K.M., S.M., and R.Y. wrote the paper.
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The authors declare no conflict of interest.
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See Commentary on page 17585.
- Abbreviations:
- CZB,
- Chatot, Ziomet, and Bavister medium;
- Hepes-CZB,
- Hepes-buffered CZB solution;
- ICSI,
- intracytoplasmic sperm injection;
- LL,
- lysolecithin;
- SOAF,
- sperm-borne oocyte-activating factor.
- © 2006 by The National Academy of Sciences of the USA
