Gross, histological and histochemical investigation of the stomach of the Eurasian stone curlew (Burhinus oedicnemus) and pied king fisher (Ceryle rudis)

Abstract

The structure of the stomach is correlated to the type of the food of the organism. This study investigated the gross, microscopic, histochemical and ultrastructure of the stomach of the stone curlew and pied king fisher. Six adult stone curlew and six adult pied kingfisher of both sexes were used. The results revealed that, the proventriculus was truncated cone- shaped organ in curlew; while, it is very short tube-like in kingfisher. The mucosal surface of the proventriculus has proventricular papillae over its entire surface.  The ventriculus was biconvex lens in shape in curlew; while, in kingfisher it is sac-like organ. The thick muscular wall in curlew consisted of the Crassus caudodorsalis, C. cranioventralis muscles, tenuis craniodorsalis and caudoventralis; while, the wall is thin in kingfisher so this organization is unclear. The proventriculus and ventriculus in both studied birds have folds of the tunica mucosa lined by columnar epithelium.  Simple tubular glands occupied the lamina propria. The ventricular glands were lined by simple columnar cells. The proventricular glands were situated between the inner and outer layers of the lamina muscularis mucosae. The tunica submucosa was very thin in the proventricular wall; while, in the ventriculus, it was not separated from the lamina propria due to the absence of any lamina muscularis mucosae. Musclosa of ventriculus in kingfisher consisted of three layers: an internal longitudinal layer, a middle circular layer and an external layer of longitudinal smooth muscle fibers; while, in curlew the outer longitudinal layer was absent. In conclusion, the study detected many variations in the stomach structures of birds subjected to study and these differences could be due to the differences in food habit. Further studies should be carried out for more understanding the physiological process of digestion and nutrient absorption in these birds.