Ultrastructure of sperm development and mature sperm morphology in three species of commensal bivalves (Mollusca: Galeommatoidea)

Abstract

Ultrastructural features of the ovotestes, spermatogenesis, and the mature sperm are described for three galeommatid bivalves, Divariscintilla yoyo, Divariscintilla troglodytes, and Scintilla sp., from stomatopod burrows in eastern Florida. All three species yielded similar results except with respect to mature sperm dimensions. The ovotestis contains three types of somatic cells within the testicular portion: flattened myoepithelial cells defining the outer acinal wall; underlying pleomorphic follicle cells containing abundant glycogen deposits; and scattered, amoeboid cells containing lysosomal-like inclusions which are closely associated with developing sperm. Early spermatogenesis is typical of that reported from other bivalves. In contrast, the late stages of spermiogenesis involve the migration and gradual rotation of the acrosomal vesicle, resulting in a mature acrosome tilted about 70° from the long axis of the cell. The mature sperm possesses an elongated, slightly curved nucleus; a subterminal, concave acrosome with a nipple-like central projection; five spherical mitochondria and two centnoles in the middlepiece; and a long flagellum. The rotational asymmetry and the presence of perimitochondrial glycogen deposits in these sperm are unusual in the Bivalvia and may be associated with fertilization specializations and larval brooding common among galeommatoideans.

On bivalve phylogeny: a high‐level analysis of the Bivalvia (Mollusca) based on combined morphology and DNA sequence data

“…Hodgson & Burke 1988); Spondylus sinensis based on S. nicoharicus ; Limaria hians based on L. fragilis ; Atrina pectinata based on A. vexillum ; Neotrigonia bednalli (Healy 1989); Neotrigonia margaritacea (Healy 1996b); Psilunio littoralis based on Velesunio ambiguus (Healy 1989); Cardita calyculata based on Cardita muricata (Healy 199Sb); Astarte castanea coded based on crassatellids2 Eucrassatella cumingii, E. kingicola, and Talabrica aurora (Healy 1995b); Galeomma turtoni based on Divariscintilla yoyo, D. troglodytes, and Cintilla sp. (Eckelbarger et al 1990); Lasaea sp. based on L. subviridis (0 Foighil 1985a); Codakia orhicularis based on C. punctata (Healy 1995a); Chama gryphoides based on C. macerophylla (Hylander & 2This coding assumes monophyly of Crassatellidae + Astartidae, and that the sperm anatomy described for 3 crassatellids is the groundplan for the common ancestor of…”

“…The temporary acrosorne has not been observed in any non-anomalodesmatan bivalve. Anterior act-osomal vesicle: (0) (0 Foighil 1985a,b;Eckelbarger et al 1990). Anterior nuclear fossa: a/p (Healy 1990).…”

Spermatozoan ultrastructure in the trigonioid bivalveNeotrigonia margaritacea Lamarck (Mollusca): Comparison with other bivalves, especially Trigonioida and Unionoida

“…Nevertheless it was observed that the proacrosomal vesicles of N. Gharagozlou-Van Ginneken & Pochon-Masson, 1971;Popham, 1979;Franz6n, 1983;Healy, 1989Healy, , 1995Eckelbarger et al, 1990;Hodgson et al, 1990), that is, composed of round mitochondria surrounding a pair of orthogonally arranged centrioles (an arrangement characteristic of aquasperm in general; cf. Jamieson, 1987).…”

“…All other bivalves possess a single, conical acrosomal vesicle, although during sperrnatogenesis in most of these species, multiple proacrosomal vesicles (which fuse to form the definitive acrosomal vesicle) are produced by the Golgi complex (see Longo & Dornfeld, 1967;Longo & Anderson,1969;Popham, 1979;Franz6n, 1983;Healy, 1989Healy, , 1995Hodgson & Bernard, 1986;Eckelbarger et al, 1990;Hodgson et al, 1990). The morphology of the mature acrosome of unionoids has been studied by various workers but with differing interpretations.…”

Germ Cell Differentiations During Spermatogenensis and Taxonomic Values of Mature Sperm Morphology of Pinctada martensii (Bivalvia, Pteriomorphia, Pteriidae)

“…Utrastructural studies have been described the spermatogenesis and spermatozoa of a number of bivalve species using electron microscopy (Longo and Dornfelds, 1967;Longo and Anderson, 1969;Popham, 1979;Bernard and Hodgson, 1985;Hodgson and Bernard, 1986;Healy, 1989;Eckelbarger et al, 1990;Eckelbarger and Davis, 1996;Gaulejac et al, 1995;Chung and Ryou, 2000;Chung et al, 2007Chung et al, , 2010.…”