Histological and histochemical studies on the esophagus, stomach and small intestines of varanus niloticus [electronic resource].

Includes references.

Information on the digestive system of the reptiles is based on relatively few studies on some of the now present 7500 reptilian species. Yet, the gap between our understanding of the major similarities and / or differences between the mammalian and reptilian digestive system does not seem satisfiable. The aim of the current study was to investi¬gate the morphological structure of one of the most common reptilian species in Egypt, Varanus niloticus or Nile moni¬tor. Specimens for histological exami¬nation were collected from the esopha¬geus, stomach and small intestine of the Nile monitor and pro-cessed for pa¬raffin embedding. Sections were stained with haemat-oxylin and eosin for general morpho-logy. Periodic Acid Schiff's (PAS) and Alcian Blue (AB) staining methods were applied to detect the different types of the mucous con¬tents of the gastro-intestinal tract. Some paraffin sections were stained with Grimelius silver impregnation tech¬nique for localization of the enteroendo¬crine cells.The folded esophageal mucosa had ciliated columnar epithelium with muc¬ous secreting goblet cells, which stained positive with PAS and AB. The esophageal mucosa was folded and the lining epithelium was ciliated columnar epithelium with mucous se¬creting goblet cells, which stained posi¬tive with PAS and AB. The stomach was divided into fundic and pyloric regions. The mucosa was thrown into gastric pits, into which the gastric glands opened. The surface epithelium was mucous secreting co¬lumnar cells and stained positive with PAS but negative with AB. The fundic gland was made by oxynticopeptic cells and few mucous cells, while the entire pyloric gland was made by mucous cells stained positive for both PAS and AB. The small intestine showed many villi but occasional poorly developed intestinal crypts were. The intestinal mucosa was lined with absorptive co¬lumnar epithelium with goblet cells, which stained positive with PAS and AB. Enteroendocrine cells were of different shapes; rounded, spindle, oval

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