Morphogenetic effects of vitamin A on the regenerating tail fin of the teleost fish, Oreochromis niloticus

AbstractThe present study was performed to investigate the effects of vitamin A (VA) on tail fin regeneration of the teleost fish, Oreochromis niloticus. Following amputation, the tail fin undergoes a regenerative process which leads to an apparently faithful replacement, both in shape and size of the missing part. However, analysis of the fin skeleton of whole mount preparations of normal (unamputated), control, and treated tail fins revealed that, fin regenerates were not perfect copies of the missing part, and that the distance and the number of ray segments between the amputation plane and the first dichotomy were higher in treated tail fins than in control and unamputated fins. This suggests that VA can affect patterning formation of the regenerating tail fin. Vitamin A has morphogenetic effects on the regenerating fin by increasing the number of ray segments as well as it exhibits a marked reduction in the amount of tissue between rays that leads to fusion of adjacent rays

Comparative study on the tongue of Bufo regularis and Chalcides ocellatus in relation to their habitats

The present study investigated the structure of the tongue of the toad, Bufo regularis and the lizard, Chalcides ocellatus. They have different feeding habits and live in different habitats. The tongue of the toad contains two types of lingual papillae; fungiform papillae and filiform papillae. The fungiform papillae are usually scattered among the filiform papillae and are believed to function in gustation and in the secretion of salivary fluid. Scanning electron microscopical studies revealed that no ciliated cells were observed on the surface of the filiform papillae or in the surrounding area of the sensory disc. In C. ocellatus the tip of the tongue is bifurcated and keratinized. The dorsal surface of the tongue is covered with several types of papillae; irregular, scale and ridge-shaped. Taste buds were present in the epithelium of the tongue. The lingual glands consist of mucous cells that form crypt-like invaginations between papillae. The present study revealed that there is a marked correlation between the structure of the tongue of both B. regularis and C. ocellatus and habitats and feeding mechanism of the two species

Ultrastructural study of the effect of heavy metals on the regenerating tail fin of the teleost fish, Oreochromis niloticus

The present study was performed to investigate, ultrastructurally the effect of heavy metals on the regenerating tail fin of the teleost fish, Oreochromis niloticus, revealed that, in the tail fins of the specimens treated with lead (Pb) at 0.005 mg/l, at the fifth day postamputation, the blastema cells are displayed shrinkage nuclei, much chromatin, pyknotic mitochondria and vacuolated cytoplasm, whereas in the specimens treated with 0.025 mg/l, the blastema cells showed multi-nucleoli, different size and shape of mitochondria and swollen rough endoplasmic reticulum. In the tail fins of the specimens treated with cadmium (Cd) at 0.005 mg/l, the nuclei of the blastema cells showed little chromatin, also, a blood vessel with abnormal red blood cells was recognized in the neighborhood layer of the blastema cells, whereas in the specimens treated with 0.025 mg/l the nuclei of the blastema cells are arranged adjacent to the inner membrane of the nuclear envelope. The cytoplasm of these cells displayed swollen rough endoplasmic reticulum, with the transformation of their cisternae into circular arrays, vacuolated cytoplasm, pyknotic mitochondria and suppression of differentiation. In the tail fins of the specimens treated with mercury (Hg) at 0.0006 mg/l, the blastema cells showed dense scattered lysosomes, pyknotic mitochondria, progressive damage in the cytoplasmic organelles leaving large vacuolated space and complete autolysis of cells. In the tail fins of the specimens treated with Pb at 0.005 and 0.025 mg/l and Cd at 0.005 and 0.025 mg/l, at the seventh day postamputation, the lepidotrichia forming cells have dense patches of irregular lysosomes, swollen and degranulated rough endoplasmic reticulum, pyknotic mitochondria and vacuolated cytoplasm. In the tail fins of the specimens treated with Hg at 0.0006 mg/l, showed deformation of the lepidotrichia forming cells, there was an invasion of leucocytes and lysosomes. A progressive damage in the cytoplasmic organelles and in the fiber bundles of bones was also found. Also, the presence of collagen fibers as pathological condition