Comparative studies on the histology and ultrastructure of the siphons of two species of Tellinidae (Mollusca: Bivalvia) from Brazil

Despite the great importance of the siphons for infaunal bivalves, only a few studies have examined their tissues using histology techniques or scanning electron microscopy. In the present study, the siphons of Tellina lineata Turton, 1819 and Macoma biota Arruda & Domaneschi, 2005 were investigated. The siphon walls are composed by a series of muscle sheets of longitudinal ("L"), circular ("C") and radial ("R") fibers, with a clear pattern common to both species: there is a main median longitudinal layer (Lm), and two peripheral circular layers, one inner (Ci) and one outer (Co), near the epi...