Fixation of the Crystalline Style of Bivalve Molluscs (Anodonta Sp.) for Scanning Electron Microscopy

Abstract

In the digestive tract of certain bivalves such as oysters and mussels, a structure known as the crystalline style functions as a grinding mechanism for the breakdown of large food particles. The style is located in the posterior portion of the bivalve stomach where it is extruded from the style sac and slowly rotated across the interior of the stomach. It grinds against a hardened portion of the stomach wall known as the gastric shield. The rotation of the style serves to draw the contents of the stomach through this organ, thus taking the place of any musculature that would otherwise be necessary. In several of the species that produce this structure, the style is re-absorbed when the bivalve is not feeding. This has lead to the proposal that the style serves as a nutrient source in starvation condition as well as an organ for maceration. The style is extruded again when food is available, incorporating in its structure the first food particles to enter the stomach.