Essential Roles of the Sperm Centrosome in Human Fertilization: Developing the Therapy for Fertilization Failure due to Sperm Centrosomal Dysfunction

Invited Review for the 90^th Anniversary

Essential Roles of the Sperm Centrosome in Human Fertilization: Developing the Therapy for Fertilization Failure due to Sperm Centrosomal Dysfunction

YUKIHIRO TERADA,¹ GERALD SCHATTEN,² HISATAKA HASEGAWA¹ and NOBUO YAEGASHI¹

¹Department of Obstetrics and Gynecology, Tohoku University School of Medicine, Sendai, Japan
²Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA

Fertilization is a lengthy process that culminates when the male and female pronuclei fuse in the oocyte cytoplasm. The final stage of fertilization is mediated by the sperm centrosome, which induces microtubule organization into the first mitotic spindle. Despite its critical role, only few functional analyses of the sperm centrosome have been performed until now. Here, we review the recent literature with regard to sperm centrosomal functions during human fertilization, as well as the development of functional assays for the human sperm centrosome. We then address various challenges for fertilization failure resulting from centrosomal dysfunction. Cytological analyses of oocytes that fail to complete fertilization following intracytoplasmic sperm injection (ICSI) have shown that some cases are associated with sperm centrosomal dysfunction. Human sperm can organize a sperm aster even within the oocytes of other mammals. This property has been utilized as a means of assessing the centrosome function. In some patients with teratozoospermia, the sperm does show evidence of impaired centrosomal function. Some clinical and basic challenges for overcoming the fertilization failure caused by sperm centrosomal dysfunction have been reported. The sperm centrosome plays an important role in the phase of the fertilization process after ICSI, i.e. within the oocyte's cytoplasm. The next generation of assisted reproductive technologies (ART) will likely incorporate analyses of sperm centrosomal function as well as techniques designed to counter sperm centrosome dysfunction.

keywords —— assisted reproductive technique; fertilization; intracytoplasmic sperm injection; infertility; sperm centrosome

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Tohoku J. Exp. Med., 2010, 220, 247-258

Correspondence: Yukihiro Terada M.D., Ph.D., Department of Obstetrics and Gynecology, Tohoku University School of Medicine, 1-1, Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan.

e-mail: terada@mail.tains.tohoku.ac.jp