Abstract: 41

MICROTUBULE ORGANIZATION IN RABBIT OOCYTES, ZYGOTES AND INTRACYTOPLASMIC INJECTION WITH HUMAN SPERM.

YUKIHIRO TERADA^{1 *}, CALVIN SIMERLY^{1 *}, LAURA HEWITSON^{1 *}, GERALD SCHATTEN^{2 *}
Dept. of Reproductive Science, Oregon Regional Primate Res. Ctr., Beaverton, Oregon ¹
Dept. of OB/GY, and Cell and Devel. Biol. Oregon Health Sci. Univ., Portland, Oregon ²

In this study, we characterized microtubule organization and chromatin configurations in rabbit oocytes after intracytoplasmic injection with human sperm and following in vivo and in vitro rabbit fertilization. In unfertilized oocytes, an anastral, barrel shaped meiotic spindle oriented radially to the cortex was observed. After sperm incorporation, microtubles form a radial aster from the sperm head and also organize a monaster around the female pronucleus. The microtubules extending from the decondensed sperm head participated in pronuclear migration while those organization around the female pronucleus may be important to pronuclear centration. Support for these observations is found in parthenogenetically activated oocytes, wheel microtubule arrays were organized around the single female pronucleus that formed following activation. These observations support a biparental centrosomal contribution during rabbit fertilization. In rabbit oocytes injected with human donor sperm, an astral array of microtubles radiated from the sperm neck and enlarged as the sperm head underwent pronuclear decondensation. Gamma-tubulin was observed in the center of the sperm aster. We conclude that the rabbit oocyte exhibited a blended centrosomal contribution necessary for completion of fertilization and that rabbit oocyte may be a novel model for assessing centrosomal function in human sperm and spermatogenic cells (spermatocytes, spermatids) following ICSI.

    This abstract is being presented on Sunday, August 1 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.