ABSTRACT
The morphological features (i.e. descriptors beyond total length) of cetacean spermatozoa have been reported (albeit often minimally) for only 14 of the nearly 80 extant species. These 14 species represent six families, one from the suborder Mysticeti and five from the suborder Odontoceti (Matano et al. 1976; Fleming et al. 1981; Mogoe et al. 1998; Beilis et al. 2000; Kita et al. 2001; Miller et al. 2002; Fukui et al. 2004; Meisner et al. 2005). Two investigations have been comparative studies of cetacean spermatozoa, one employing light microscopy (LM) and scanning electron microscopy (SEM) (Kita et al. 2001) and the other using LM, SEM and transmission electron microscopy (TEM) (Miller et al. 2002). In addition, Meisner et al. (2005) included five cetaceans in their SEM examination of sperm head morphology of 36 mammalian species. Although most accounts have been of epididymal spermatozoa, Mogoe et al. (1998) described sperm from the vasa deferens. Others examined spermatozoa collected using electroejaculation (Fleming et al. 1981) or trained medical behaviors (Miller et al. 2002). Fukui et al. (2004) noted the occurrence of significant morphological changes secondary to cryopreservation. This chapter reviews the morphological and ultrastructural characteristics reported for cetacean spermatozoa and provides new information on spermatozoa from some species investigated previously, as well as from five other species, including representatives of two additional families. Lastly, we offer observations on the ultrastructural effects of cryopreservation.
