Histological Evidence for the Presence of a Glandular Stomach in the Mudskipper Scartelaos histophorus From the Mekong Delta, Vietnam.

This study describes the gross anatomy and histological organization of the digestive tract of the mudskipper Scartelaos histophorus from the Mekong Delta, Vietnam. Thirty adult specimens were collected from intertidal mudflats, and the digestive tract was examined using gross anatomical observation and routine paraffin histology with haematoxylin and eosin staining. Gross anatomical observation differentiated the digestive tract into the oesophagus, stomach, intestine and rectum, whereas histological examination focused on the stomach, intestine and rectum. The stomach was characterized by prominent mucosal folds, a well-developed lamina propria and numerous gastric glands. These features provide strong histological evidence for the presence of a glandular stomach in S. histophorus. The intestinal mucosa formed long and slender folds lined by columnar epithelial cells and mucus-secreting cells, whereas the rectum showed shorter mucosal folds and a comparatively thick muscular layer. The regional differentiation of the stomach, intestine and rectum suggests structural specialization of the digestive tract in relation to the omnivorous feeding habit of this amphibious fish. These findings provide the first histological description of the main digestive regions in S. histophorus and contribute to comparative knowledge of digestive morphology within Oxudercidae.