SUBMICROSCOPIC MATHEMATICAL EVALUATION OF SPERMATOZOA IN ASSISTED REPRODUCTION .1. INTRACYTOPLASMIC SPERM INJECTION (NOTULAE-SEMINOLOGICAE-6)

After a large introduction concerning the influence of sperm quality i n the success of in vitro fertilization, the debated problem of the im portance of the sperm quality in intracytoplasmic sperm injection is i nvestigated. The spermatozoa are studied by electron microscopy, and t he results evaluated by the formula of Baccetti et al. (1995). The qua lity of spermatozoa has been correlated with the success of ICSI. The first conclusion has been that ejaculates which produced embryos conta ined higher percentages and overall higher total number of 'healthy' s permatozoa than those which obtained fertilizations arrested at the tw o pronuclei stage, or showed no fecundation at all. A second conclusio n was that the quality of sperm organelles is mainly involved in the o ocyte activation, but after the 2 pronuclei stage, segmentation usuall y proceeds with few influences from sperm quality. The highest involve ment of spermatozoa is therefore the initiation of oocyte activation. A third conclusion confirmed the need of ultrastructural evaluation of sperm cell organization, deeply investigating the inner organelles. M oreover, we observed that the head organelles are more involved that t he tail ones. Three acrosomal characteristics are concerned: the shape , the dimensions and the content. All of them are significantly better in the oocyte activating than in non activating spermatozoa. Also the nuclear shape and the status of the chromatin (frequently strictly in terdependent) are significantly concerned with the oocyte activation a nd with the embryo segmentation. In the tail, the mitochondrial shape is significantly different in activating and not activating spermatozo a, and also in those producing embryo segmentation. Moreover, the abse nce of dynein arms seems to be determinant in impeding the oocyte acti vation.