HISTOLOGY AND ULTRASTRUCTURE OF THE GUT OF THE TILAPIA (TILAPIA SPP.), A HYBRID TELEOST

The morphology of the intestine has been studied in a species of warm water fish, Tilapia spp., a hybrid teleost of notable economic importa nce. Light and electron microscope results show that the intestine is a relatively undifferentiated muscular tube lined with a simple column ar epithelium interspersed with goblet cells. The proximal region has a greater surface area, manifested by elongated mucosal ridges. The en terocytes are covered apically with uniform microvilli and exhibit the typical ultrastructural features of pinocytosis, namely extensive inv aginations of the luminal plasma membrane and massive accumulation of vesicles in the apical cytoplasm. The distal intestine mucosa is thinn er and less elaborately folded and consists of columnar cells with sho rter and sparser microvilli. Their supranuclear cytoplasm contains abu ndant clear vacuoles. Numerous endocrine cells can also be seen. Regio nal cellular ultrastructural features are correlated with digestive fu nctions.