Fine Structural Changes of Mitochondria in Cerebral Edema and Dehydration

Abstract

Mitochondrial changes in the experimental cerebral edema and dehydration of the rabbit were observed with the electron microscope. Cerebral edema was produced in three animals by the Weed's method, the intravenous injection of distilled water (50cc/kg). Cerebral dehydration was produced in three animals by the intravenous injection of 30% urea solution (3.0g of urea/kg).
In the cerebral edema the mitochondria in astrocytes and those in nerve cells showed different fine-structural changes. In the enlarged pale astrocytic cytoplasm and the cytoplasmic processes, most mitochondria were swollen round or ellipsoidal. The mitochondrial matrix was extremely swollen, electron-lucent and homogeneous, and the cristae were irregular in their arrangement. The swelling of the astrocytic mitochondria is probably due to the ambient hypotonicity in the cytoplasm of astrocytes swollen in cerebral edema. Although the nerve cells themselves in cerebral edema were not enlarged, their mitochondria were swollen into irregular shapes and their matrix was partially pale and not homogeneous. These mitochondrial alterations of nerve cells in cerebral edema seemed to show a degenerative process in the nerve cell secondarily caused by the intracellular edema of the astrocyte.
In cerebral dehydration, astrocytes were shrunken, but nerve cells not. Mitochondria in astrocytes and those in nerve cells were both shrunken and their matrices become extremely dense. The present study indicates that mitochondria in astrocytes and nerve cells are especially sensitive among intracellular organelles, and can easily change their shape and structure according to the altered metabolism in cerebral edema.