Abstract Melone, G., Lora Lamia Donin, C., Cotelli, F. 1980. The paraspermatic cell (atypical spermatozoon) of Prosobranchia: a comparative ultrastructural study. (Institute of Zoology, University of Milan, Milano, Italy.) — Acta
zool. (Stockh.) 61(4): 191–201. The ultrastructure of the paraspermatic cells (atypical spermatozoa) in the male genital tracts of nine species of marine Prosobranchia is described. These cells derive from the same germinal line as the typical spermatozoa, and seem to be homogeneous
in their general constitution. In all nine species the paraspermatic cells are characterized by the presence of granules. Axonemes are present in all except one species. Various kinds of paraspermatic cell movements are described; three of the nine species have not yet demonstrated any motility.
The significance and the function of paraspermatic cells are discussed.