Mohammad Taghi Sheibani - Department of Basic Science, faculty of veterinary medicine, university of Tehran, Tehran, Iran
Omid Zehtabvar - Department of Basic Science, faculty of veterinary medicine, university of Tehran, Tehran, Iran
Mehdi Moghim - Caspian Sea National Reasearch Center, Iranian Fisheries Research Organization, Sari, Iran

Digestive tract is one of the most important body organs in fishes and the pyloriccaecum is an important organ involved in absorption of foods in Huso huso. The aimof the present study is diagnosing precise microscopic structures of this organ in twomonth old Caspian Sea beluga (H. huso). The samples were obtaied from sturgeonartificial rearing stations in the Saari and after fixation into 10% formalin, histologicalsections of 6 microns were prepared based on routine histological technique. Theystained using hematoxylin and eosin and studied under light microscope. The resultsshowed that pyloric caecum as a pyramidal organ locating anterior to intestine.Internal surface is highly folded possessing short villi with a simple columnarepithelium and goblet cells. Lamina propria is loose connective tissue containingmany simple to branched caecal glands. A thin muscularis mucosa separates mucosafrom submucosa. The muscular layers are composed of a circular and longitudinallayers surrounded by serosa with squamous cells. As a conclusion presence of afolded mucosa, an epithelium similar to intestines and many secretory cells indicatingof important role of this organ in absorption of food stuffs.

Beluga, Caecum, Histology