ULTRASTRUCTURAL-STUDY OF THE DISTAL PART OF THE INTESTINE OF ONCORHYNCHUS-MYKISS - ABSORPTION OF DIETARY-PROTEIN

Ultrastructural analysis of the absorbent cells in the distal intestine of the rainbow trout Oncorhynchus mykiss revealed the presence in this zone of two types of cells: vacuolated and non-vacuolated. The former are characterized by numerous microvilli, large numbers of pinocytotic vesicles, a well-developed tubulovesicular network, and numerous lysosomes. This cytological feature suggests that these cells are involved in the uptake of dietary protein macromolecules by pinocytosis. The findings of this study provide important information that should prove useful in further comparative analyses of this portion of the intestine of trout fed on experimental diets.