Light and electron microscopic evaluation of the role of centrosome in early embryonic development

Intracytoplasmic sperm injection (ICSI) is a common method used for infertility treatment. However, in some cases, after fertilization, it may result with early cleavage abnormalities. Embryonic development proceeds with regular mitotic divisions. During, this process paternally inherited centrosome acts an importent role. Some investigators suggest that abnormal sperm centrosome may relate to early cleavage abnormalities of embryo. In our study, we collected ejaculated sperm samples from male partners of couples whose embryos showed high incidance of abnormal cleavage as a result of ICSI treatments. These samples were investigated at microscopic level comparing with samples of fertile men. Samples were examined with light and electron microscopy. Furtermore, expression of sentrosome proteins sentrin and speriolin were investigated with immunofluorescence staining. As a result of investigations it was seen that while morphological results of some patients were within normal range, some patients showed low morphological rates. Insignificant results on expression levels of centrosome proteins were found. In some patients, high percentage of neck anomalies were detected in TEM examination. Especially in two patients, rate of double-necked spermatozoa was high and therefore numbers of centriole structures were seen more than one. We suggested that in these two cases, possibility of being double-necked of selected spermatozoa for ICSI was high. When this sperm was used in ICSI, zygote might have got many centrioles and this could have led to fragmentations in cleavages forming multipolar mitotic spindles. We suggest that TEM examination of spermatozoa can be a guiding method to assisted reproductive techniques in cases of unexplained infertility. Key Words: Sperm, centrosome, transmission electron microscope, centrin, speriolin