Morphological and histological studies of the adrenal gland in the Japanese quail (Coturnix japonica).

The adrenal gland is a vital endocrine gland that secretes many important hormones in everyday bird life. The adrenal gland of the Japanese quail is grossly located ventromedially the corresponding kidney and has a creamy to yellow color. The quail gland is surrounded by a capsule and contains some ganglionic cells, and the capsule is characterized by the presence of chromaffin cells. The adrenal gland is subdivided into three concentric zones: subcapsular, peripheral, and central. The parenchyma consists of interrenal tissue, chromaffin islets, and blood sinusoids. The interrenal cells contain lipid droplets, are arranged in cords, and rest on the basement membrane. Chromaffin cells are categorized as two types: epinephrine (E) and norepinephrine (NE) cells. These cells contain the granules, and are characterized by the presence of lipid droplets. In this study, the interrenal tissue was found to have a higher proportion of chromaffin cells in quail as compared with other birds, which is attributed to the fact that the Japanese quail is a migratory bird. Therefore, the present investigation aims to provide a detailed study on the adrenal gland in the Japanese quail to help physiologists understand the gland's function and the pathologist to determine the implications for the differential diagnosis of adrenal gland tumors. HIGHLIGHTS: The adrenal gland is subdivided into three concentric zones: subcapsular, peripheral, and central. The interrenal cells contain lipid droplets, are arranged in cords. Chromaffin cells are categorized as two types: epinephrine (E) and norepinephrine (NE) cells. These cells contain the granules, and are characterized by the presence of lipid droplets. The interrenal tissue was found to have a higher proportion of chromaffin cells in quail because it is a migratory bird.