Structure of mammalian spermatozoa in respect to viability, fertility and cryopreservation.

Morphological assessment of spermatozoa has a long history and it is generally accepted that specific morphologic structural deviations correlate with male sub- and infertility. Although many different and also new methods are used in semen analysis, light microscopy is still used for routine morphological evaluation. This paper gives an overview about the detailed structure of physiological mammalian spermatozoa as well as the most common morphological deviations in correlation to fertility. This should be the basis for explanation of problems resulting from semen cryopreservation. General aspects of semen cryopreservation should be regarded before to facilitate the understanding of methods and mechanisms.