Abstract
A series of studies was carried out to elucidate the relationship between the microscopic anatomy of the alimentary canal and the food habits in reptiles. Three reptiles were chosen according to different feeding habits, Uromastyx is a herbivouous, Chameleon is an insectivorous, while Crocodilys is a carnivorous reptile. So, it is obvious that the anatomy as well as the histology of the alimentary tract of reptiles demonstrate certain specific characteristics of functional adaptations as a reflection of the herbivorous, carnivorous and insectivorous mode of feeding. The anatomical and histological study of the alimentary canal of Uromastyx aegyptiaca was carried out. A comparison between the different histological structures found and those known in other reptiles was done. The straight oesophagus is lined with ciliated epithelium and goblet cells, leading to the stomach which consists of two portions, fundic or oxyntic and pyloric or mucous. The small intestine is comparatively short although the animal is purely herbivorous. It consists of the duodenum and ileum. The duodenual mucosa is in the form of leaf-like villi provided with shallow branched Lieberkuhn crypts at their bases. The ileum is devoid of found glands. The large intestine is formed of a well developed large caecum, colon and rectum. At the posterior edge of the caecum there is a small blind sac which is considered as the appendix. The caecum which is devoid of glands is lined with simple columnar cells of a special type. While the ileo -caecal valve is in the form of a characteristic well developed protrusion, the caeco-colic valve is formed of a flap arising from one side. The mucosa of the colon is folded and lined with goblet and columnar cells, while that of the rectum is, more or less, straight and is rich in goblet cells and lymph spaces. The distribution and localization of different carbohydrate categories (PAS-positive material, mucopolysaccharides) were studied in the mucosal epithelium of the alimentary canal of Uromastyx aegeptiaca. The goblet cells of the oesophagus are rich in acid mucpolysacharides, those of the small and large intestine contained smaller amounts. Neutral mucpolysacharides were found in small to moderate amounts, being most obvious in the gastric mucosa. Mode of feeding as well as habitat, show, more or less a close similarity in the histochemical pattern of their gut mucosa as regards to the distribution and localization of proteins and nucleic acids. [Moustafa Zaher, Abdel-Wahab El-Ghareeb, Hamida Hamdi, Azza Essa and Suad Lahsik. Anatomical, Histological and Histochemical Adaptations of the Reptilian Alimentary Canal to Their Food Habits: I. Uromastyx aegyptiaca. Life Sci J 2012;9(3):84-104]. (ISSN: 1097-8135). http://www.lifesciencesite.com. 13