HISTOLOGICAL STUDY OF ACIPENSER PERSICUS ALIMENTARY CANAL DURING EARLY LIFE STAGES

Histological study of alimentary canal of Persian sturgeon was conducted during early life from hatching to 56 days old by light microscope. Some hours after hatching, in anterior part, rudimentary eye and brain were visible, also in posterior part was completely filled with acidophil yolk. Mouth and anal were not clear. In 5-7 days after hatching all parts of the alimentary canal except stomach were roughly anatomically complete, as though in comparison with the hatching time the amount of acidophil yolk was less. At this stage, mouth was covered by stratified squamous epithelium in which several number of tast buds were visible and also rudimentary part of esophagus was squamous to pseudostratified columnar epithelium and in terminal part was columnar to ciliated pseudostratified columnar epithelium. In 8-9 days after hatching, the alimentary canal was structurally complete and two parts of stomach i.e. glandular stomach (cardia) and non-glandular stomach (pyloric) were more clear. The glandular stomach epithelium was simple columnar to ciliated pseudostratified columnar epithelium, while pyloric stomach had simple columnar to pseudostratified columnar epithelium. In 9 days after hatching, external food with a lot of yolk were visible in alimentary canal, which indicates endo-exogenous feeding. In I I-12 days after hatching a lot of external food i.e. daphnia were visible in alimentary canal .In 14 days after hatching pyloric caeca was appeared and in 40 days conical teeth was observed. In the primitive stages of life, the glycoprotein secretions belong to simple columnar cells (interior part of esophagus &some parts of intestine), while through age increase, this secretions belong to apical cells of simple columnar and also goblet cells. The beginning of active feeding of Persian sturgeon larvae was occurred in 9 to 11 days after hatching. Following the development, there was no special alternation except thickness increase of epithelium, muscular layer, connective tissue of lamina propria and increase of epithelial folds of intestine.