Electron micrograph of epithelial cells of the parotid gland of the gerbil, prepared by rapid freezing and freeze substitution. Microvilli and microplicae, which expand the extracellular surface alon...

In the basal region of polarized epithelium engaged in ion transport, mitochondria are lodged between the interdigitating membranes of neighboring cells. This example is of a transverse section throu...