Ultrastructure of the digestive tract in the ophiopluteus of Ophiura sarsi

Summary

The cell composition and ultrastructure of the digestive tract of the Ophiura sarsi ophiopluteus was investigated. The digestive tract consists of three parts: esophagus, stomach and intestine. Cardiac, pyloric sphincters and anus are formed by myoepithelial cells. The cells of the esophagus are of a single type. The stomach epithelium consists of three cell types. Types 1 and 2 are common, some having large osmiophilic granules—the remains of the embryonic yolk storage. They probably function in nutrient absorbtion. Type 3 cells are characterized by a well developed rough endoplasmic reticulum and large transparent vacuoles and, perhaps, have a secretory nature. The intestine epithelium consists of three cell types. The possible functions and the fate of the cell types are discussed from a comparative perspective.

Key words:

• Ophiopluteus
• digestive tract
• TEM