Numerical Ratio of the Atypical to the Typical Spermatozoa in Viviparus and Several Other Prosobranchiata

Abstract

A. Introduction.It has been well known' since the time of Si eb old (1836) that in Viviparus there are two kinds of spermatozoa-the one a normal flagellate type having head and tail distinct (typical spermatozoa9, the other an abnormal worm-shaped type having a small quantity of chromatic substance in its head (atypical speamatozoa) ( Fig. 1. t and a).v. Br unn (1844) thought the atypical spermatozoa to be functionless and presented the hypothesis that the atypical spermatozoa is rather homologous to the egg of the hermaphroditic Prosobranchiata. M e v es (1903), in his excellent work on the' spermatogenesis of the animal, found that the atypical spermatozoa is rather normal spermatozoa produced through two maturation divisions, although the maturation divisions are different from those of the typical spermatozoa in that most of the chromatic substance is ejected from the nucleus into the cytoplasm. So he protest-1) Si e b old described the normal spermatozoa as hair-shaped, and the abnormal as worm-shaped.Meves described the normal as eupyrenous and the abnormal as olygopyrenous, as the letter have only a small quantity of chromatic substance in their head. K u sc h ak e w it s c h (1911) suggested the general terms ; typical and atypical spermatozoa, as abnormal spermatozoa are not necessarily worm-shaped nor do they necessarily have a small quantity of chromatic substance, if we take into consideration the various species of Prosobranchiata.

Spermatogenesis in Animals as Revealed by Electron Microscopy

“…Although Fukui (46) described the atypical spermatozoon in Paludina as having only one chromosome in the head, such a conclusion may have arisen from a misinterpretation of what were actually tail filaments. Morita (47,48) observed the existence of both small and large types of atypical spermatozoa in Viviparus, while the present study has confirmed at least two types with respect to the fine structure of the head.…”