Department of Zoology, Faculty of Science, Dayalbagh Educational Institute (Deemed University), Dayalbagh, Agra-282 005 (India).
In Gryllus domesticus (Linn.), the alimentary canal is of typical orthopteran type and its regions are ranked as foregut > midgut > hindgut. It is slightly longer than its body length and this morphometric feature is corresponding to its omnivorous nature. It is characterised by the presence of peritrophic membrane in midgut. The wall of posterior proventriculus is much thicker (6.75 μ) than the wall of anterior proventriculus (3.37 μ), crop (1.39 μ), oesophagus (1.12 μ), and pharynx (0.58 μ). The wall of midgut is more developed than that of fore and hindgut, except posterior proventriculus. In midgut, it is more developed in anterior (5.42 μ) than in the posterior mesenteron (3.42 μ). In hindgut, the thickness of wall is 2.62, 1.12 and 1.26 μ in rectum, colon and ileum, respectively. In anterior mesentron, the epithelium is differentiated into functional and regeneritive epithelium. This differentiation is wanting in posterior mesentron and its cells are without brush border. The thickness of intima is 0.09 μ in pharynx; 0.36 μ in oesophagus, crop and anterior proventriculus and 0.45 μ in posterior ventriculus. It is absent in midgut. In hindgut, the intima is 0.09 μ in ileum and colon, and 0.27 μ thick in rectum. The hepatic caeca are histologically identical with mesentron and provided with a few major and numerous small folds to reduce its lumen. Six rectal glands are well developed and adapted for water absorption as Gryllus domesticus is found in dry places. Its digestive glands include a pair of salivary glands which are of typical orthopteran type.
