ABSTRACT
The pyloric caeca of Asterias rubens were investigated histologically and ultrastructurally during the annual reproductive cycle, with a particular attention to the digestive epithelium.
The wall of the pyloric caeca consists of three layers: a coelomic epithelium, a layer of connective, muscular and nervous fibers, and a digestive epithelium. The digestive epithelium is composed of storage cells, zymogen cells, special-current-producers and mucocytes. The variation in the amount of zymogen cells and the relation to the feeding conditions of the animals is discussed.
Electron microscopy revealed cells protruding into the lumen. These cells are considered to be autolysing cells rejected by the pyloric caecum.
Cells resembling peritoneal cells were found at different heights in the digestive epithelium.
‘Complex bodies’ are described in storage cells; their function is discussed.
During the extensive growth of the gonads the storage cells of the pyloric caeca exhibit special features:
The granular endoplasmic reticulum shows a high synthesizing activity.
The amount of lipid drops is elevated.
