The microstructures of adrenal gland of White Rhinoceros (Ceratotherium simum) were observed by light microscopy. The results showed that the surface envelope of adrenal gland was covered with developed connective tissues whose average thickness was up to 210 μm. A large number of sinusoids were distributed between the neighboring cells. The zona glomerulose of adrenal cortex was thin and composed of columnar and cubic cells. The columnar cells were close to the edge and the cubic cells were found in the deep zone. The two kinds of cells were arranged in irregular groups. The thickness of zona fasiculata was about 3 times as much as that of zona glomerulose, and the boundary was not obvious. Cells were arranged in irregular cords. Some small lipid droplets were in the shape of small vacuolation, and distributed in the cytoplasm. The cells of zona reticularis were adjacent to medulla with which they formed a jagged boundary. Cells were in network or in enclose acini. Medullae were darkly stained and clearly distinct from the cortex. Cells were large with elliptical nuclei whose nucleoluses were significant. Cytoplasm was basophilic and stained to give blue violet appearance. A small amount of sympathetic ganglion cells were distributed in the medulla. The above results suggested that the adrenal gland structures of African white rhinoceros compared with other animals have similarities. . The rich sinusoids in capsule suggested that its blood supply was abundant, full of metabolism and endocrine activity.

Key words: Adrenal gland, African White Rhinoceros, Histology