Ultrastructure of the Esophageal Region in Schistosoma Mansoni *

Abstract

The lining of the esophagus in Schistosoma mansoni is continuous with the tegument. The luminal portion is syncytial and is connected by cytoplasmic channels to numerous nucleated cell bodies, which form the so-called esophageal gland. The esophageal region exhibits the basic tegumental pattern, but numerous modifications are seen. The surface area is greatly amplified by folds extending into the lumen, and the nucleated cell bodies are much more prominent than the surface subtegumental cell bodies. The anteriormost of the folds contain multilaminate granules similar to those seen in the tegument, while the folds in the remainder of the lining contain solid, dense granules. In the posterior region a pocket containing angulated folds but no patent lumen extends from the main portion of the esophagus. Throughout the esophagus the portions of the folds adjacent to the lumen are distended and exhibit several kinds of membrane modifications. Mitochondria are present in these distended portions. The relation of this lining to ingested host material is morphologically suggestive of a gradient of hydrolytic capabilities in the digestive tract of this organism.