An ultrastructural analysis of the mature spermatozoon of Anguispira alternata (say) (pulmonata, stylommatophora)

Abstract

Mature spermatozoa from the hermaphroditic duct of adult snails were examined using various techniques of light microscopy as well as scanning and transmission electron microscopy. The sperm are approximately 557 μm in length including a dextrally spiral head approximately 13 μm long. The head consists of an electron-dense nucleus sculptured into a double-ridged spiral and an acrosome projecting approximately 0.45 μm beyond the apex of the nucleus. The acrosome consists of a membrane-bound vesicle approximately 0.1 μm in diameter and a column of homogeneous material which extends along one side of the terminal spiral of the nucleus. This material is separated from the nucleus by the nuclear envelope. The neck region, though similar to that found in other pulmonates, possesses a unique coiled structure surrounding the central doublet of the axoneme. The midpiece axoneme possesses a 9+9+2 configuration anteriorly grading into a 9+2 pattern for the majority of its length. There are three mitochondrial helices - one primary and two secondary - in the midpiece. Only the primary helix persists throughout the midpiece.

An Ultrastructural Study of Spermatozoa of Helix Aspersa and Helix Pomatia (Gastropoda, Pulmonata)

“…Anderson & Personne (1976) have even suggested that trypsin may directly stimulate ATPase activity within the axoneme/coarse fibre complex. However trypsin treatment does not apparently elicit movement in hermaphrodite duct spermatozoa of another stylommatophoran Anguispira alternata (Atkinson, 1982). It is likely that other chemical factoid-intrinsic or extrinsic-may govern sperm motility, or at least, determine the degree of response of pulmonate sperm to stimulants such as trypsin.…”

Ultrastructure of spermatozoa in Orthalicidae (Mollusca, Gastropoda, Stylommatophora) and its systematic implications

“…Drymaeus and Bostryx sperms have nuclei markedly reduced in twisting, slender and longer, with acrosomal pedestals cylindrical and slightly higher than the rest of species from different genera investigated. The nuclear length in Drymaeus hygrohylaeus (9.6 lm) is only comparable with the one reported for Helix pomatia (10 lm) (Healy and Jamieson 1989) and Anguispira alternata (13 lm) (Atkinson 1982) since the rest of the stylommatophoran nuclei sperm length range between 5 and 8 lm. Drymaeus sperm is clearly differentiated from helicids sperms for the acrosomal pedestal substructure and presence of a subnuclear ring.…”

Dextral and sinistral Amphidromus inversus (Gastropoda: Pulmonata: Camaenidae) produce dextral sperm

“…In some species, like in A. inversus , coiling direction of the helical elements of the spermatozoa appears to be consistently dextral, as is the case in the dextral-bodied Arion hortensis Férussac, 1819, Agriolimax reticulatus (Müller, 1774), Milax sowerbyi (Férussac, 1823), Siphonaria japonica (Donovan, 1834), S. sirius (Pilsbry, 1894), and Anguispira alternata (Say, 1816) (Anderson 1982; Maxwell 1975; Bayne 1970; Sumikawa and Funakoshi 1984) and in the sinistral-bodied Bulinus globosus (Morelet, 1866), B. africanus (Krauss, 1848), and Physella acuta (Draparnaud, 1805) (Appleton and Brackenbury 1997; Brackenbury and Appleton 1991). In other species, the coiling is sinistral, like in the (dextral-bodied) terrestrial species Cornu aspersum (Müller, 1774), Oxyloma elegans (Risso, 1826) and Testacella Draparnaud, 1801 sp.…”