Transmission Electron Microscopy of the Gastrointestinal Tract of Nile Perch Lates niloticus

The ultrastructure of the gastrointestinal tract of Nile perch was described using Transmission Electron Microscopy standard procedures. Investigations revealed the presence of mucous cells, blood vessels and oil droplets plus several nerve cells and muscle bundles in the oral cavity. Further observations revealed columnar epithelial cells in the oesophagus, with a ragged surface, high electron dense cytoplasm, intercellular spaces, mitochondria and mucus granules. The lamina propria of the oesophagus was composed of loose connective tissue, blood vessels, nerve cells and several leucocytes, while the muscularis externa was composed of striated muscle bundles with the a Z line, A band and I band. The stomach was characterized by mucosal glandular cells with electron dense granules, a prominent nucleus, mitochondria, and secretory canaliculi. The liver had an isotropic parenchyma composed of several hepatocytes with a single spherical euchromatic nucleus. The exocrine pancreatic cells in the liver occurred around large blood vessels, had large centrally positioned nuclei with electron dense nucleolus, electron dense granules, Rough Endoplasmic Reticulum, and mitochondria which dominated the cytoplasm of pancreatic cells.(AU) La ultraestructura del tracto gastrointestinal de la perca del Nilo fue descrita utilizando un procedimiento estandar de Microscopia Electronica de Transmision (MET). Las investigaciones revelaron la presencia de celulas mucosas, vasos sanguineos y pequenas gotas de aceite, ademas de varias celulas nerviosas y haces musculares en la cavidad oral. Nuevas observaciones revelaron celulas epiteliales columnares en el esofago, con una superficie irregular, citoplasma elevado y electrodenso, espacios intercelulares, mitocondrias y granulos mucosos. La lamina propia del esofago se compone de tejido conectivo laxo, vasos sanguineos, celulas nerviosas y numerosos leucocitos, mientras que la muscular externa se compone de haces musculares estriados, con presencia de la linea Z, banda A y banda I. El estomago se caracteriza por presentar celulas glandulares mucosas con granulos electrodensos , un nucleo prominente, mitocondrias y canaliculos secretores. El higado presento un parenquima isotropico compuesto de varios hepatocitos con un solo nucleo eucromatico y esferico. Las celulas pancreaticas exocrinas se encontraron alrededor de grandes vasos sanguineos, presentando grandes nucleos posicionados centralmente, con nucleolos densos, granulos electrodensos en el reticulo endoplasmatico rugoso, y mitocondrias, que dominaron el citoplasma de las celulas pancreaticas.(AU)