Pheochromocytoma surrounded by adrenal cortex. The tumor cells occupy the right one-third of the image. They are polygonal in shape and have deeply amphophilic cytoplasm, vesicular nuclei and prominent nucleoli. The cells with dense eosinophilic cytoplasm are zona reticularis cells. The cells in the upper left of the image with vacuolated cytoplasm are zona fasciculata cells.