Abstract
The oesophagus and the stomach of eight Platanista gangetica whose body length is ranging from 76 to 127 cm were examined macroand light-microscopically.
The oesophagus is a distensible muscular tube and has longitudinal folds, lined with thick stratified squamous epithelium. The oesophagus bifurcates and leads to the first and the second compartments without constrictions, and the passage to the second compartment is rather straighter than that leading to the first compartment.
The stomach of Platanista consists o f three compartments between the lower end of the oesophagus and the duodenal ampulla. The first compartment is located dorsally and to the left side of the second one, and is a thick-walled muscular sac capable of considerable dilatation. Its inner surface is covered with epithelium identical to that of the oesophagus, having no glands. Thus the first compartment is nothing but a dilated sac at the lower end of the oesophagus, and it is supposed that the main function of this compartment is the storage and breakingdown of foods. The preliminary chemical digestion in the first compartment was also discussed.
The second compartm ent is a globular thick-walled sac and can be divided by a external groove and an accompanying internal crescent septum into two parts—the oral and the anal. The border between the oesophagus and the second compartment exhibits an abrupt change from the oesophageal epithelium to the glandular one. The cardiac glands were found at a very narrow zone along the border line between the oesophagus and the second compartment. The rest of the mucous membrane of the second compartment, both oral and anal parts, is occupied by a glandular structure consisting of three kinds of cells; chief, parietal and mucous cells. The ratio of the chief cells to the parietal cells is about 3: 1.
