Histomorphological study of adrenal gland in three ophidian species

Adrenal gland is studied histologically in the common krait, the cobra and the viper. It is comprised largely of cortical tissue with medulla. Chromaffin tissue is spatially distributed on dorsal surface and in the intercortical area of the adrenal gland. Percentage of dorsal chromaffin is higher in the viper and cobra than that of the krait, while that of intercoritcal chromaffin is higher in the krait than that of others. Chromaffin cells are irregular, smaller with densely granulated cytoplasm and larger nuclei than those of interenal gland. Medullary cells are larger in the cobra than those of other snakes. Cytomorphological difference between the dorsal and intercortical chromaffin is marked only in the cobra. Occurrence of larger granules in the dorsal and smaller type in the intercortical chromaffin may be related with noradrenaline and adrenaline secretion respectively. Cortical percent is higher in the krait than that of other snakes. Adrenocortical zonation is found only in the common krait and cobra. Subcapsular zone shows regular cords with radial disposition of columner cells in contrast to the irregular orientation of polygonal cells noted in the central cortex. Differences observed in general morphology and histology of adrenal gland, are possibly due to species difference.