HA19 is a high magnification EM of the basal region of several striated duct cells. Here you can see the frequent basal infoldings that increase the cell surface area for ion channels. In the cytoplasm between these membrane specializations are numerous mitochondria that provide the needed ATP to move ions against their concentration gradient. Immediately below the epithelium is a blood vessel, indicated by a lumen and a region of fenestrated endothelium, that facilitates the ion exchange. Note the basal lamina and the thin regions in the endothelial wall.