Polar Distribution of Intramitochondrial Granules of Mucosal Epithelial Cells

Evidence obtained from both biochemical and morphological studies indicates that mitochondria play major roles in maintaining intraccllular ionic stability. In the case of whole cells, as well as for isolated mitochondria, an increase in size a n d / o r number of intramitochondrial granules is associated with the stabilizing process during changes in the ionic environment. The increase in large granules within the mitochondrial matrix has been shown to be an indication of divalent cation accumulat ion (Peachey, 1954). In our own studies of mucosal tissue of the small intestine of the rat, we have noted that during high rates of oxygen consumption by jejunal slices incubated in a mixture of amino acids (Bronk and Parsons, 1966) the mitochondria of the epithelial cells frequently show an apparent increase in the size and number of intramitochondrial granules. Al though most mitochondria in any sample of tissue incubated under these conditions are highly condensed, those which have an orthodox configuration also contain larger or more numerous mitochondrial matrical granules. In the instances being described, mitochondria are widely distributed throughout the cytoplasmic regions, but those organelles exhibiting this phenomenon are primarily localized in the basal region of the cell This paper describes this apparent structural polarity in brief form.