| Affiliation: | (1) Department of Obstetrics and Gynecology, Tohoku University School of Medicine, Seiryo-machi, Aoba-ku, Sendai, 980-8574 Miyagi, Japan;(2) Department of Genetic Engineering, School of Biology-oriented Science and Technology, Kinki University, Uchida, Wakayama;(3) Unit of Anatomy and Cell Biology, Department of Animal Sciences, Kyoto University, Kyoto, Japan |
| Abstract: | Aim In most mammalian fertilization, the sperm introduces the centrosome, which acts as a microtubule organizing center (MTOC) and is essential for pronuclear movement. In rabbit fertilization, biparental centrosomal contribution in microtubule organization has been suggested. Methods To reveal the function and inheritance of the centrosome during rabbit fertilization, we compared microtubule organization and early embryonal development following intracytoplasmic sperm injection (ICSI) with and without sperm centrosome. Sperm centrosome was removed by sonication, and the isolated sperm head was injected by a Piezo-driven micromanipulator. Samples were studied by light microscope after immunocytological stain. Results The sperm aster formation was observed 2–3 h after ICSI with intact sperm. In contrast, microtubules were organized between the male and female pronudeus without a nucleation site in the eggs after ICSI with an isolated sperm head. In the late pronudear stage following ICSI with an isolated sperm head, microtubule organization was the same as in late pronudear stage eggs after intact sperm injection. The first mitotic spindle was organized in eggs following ICSI with an isolated sperm head, as observed in eggs following ICSI with an intact sperm. Conclusions These results indicate that the MTOC is in oocyte cytoplasm during fertilization and fulfils the function when the sperm centrosome is absent. |
