Light micrograph of the cells in the medulla (innermost part) of an adrenal gland. The cells contain numerous granules (many fine purple dots) in their cytoplasm. These granules contain hormones that are released when the cells are stimulated by the sympathetic nervous system. The adrenal medullary cell nuclei are the larger round blue-purple circles. Haematoxylin and eosin stained tissue section. Magnification: x400 when printed at 10cm wide.