Rapid freezing of deep cerebral structures for electron microscopy.

A method is described for the investigation of deep cerebral structures by freeze-substitution. The head of a mouse is sectioned in a guillotine-like apparatus. The exposed surface is subjected to freeze-substitution. Electron micrographs prepared from this material exhibit under a layer of sheared tissue, a layer of tissue comparable with that observed previously in micrographs of the cerebral and cerebellar cortices subjected to freeze-substitution of their natural surfaces. By varying the plane in which the head is sectioned any structure in the brain can be made accessible to freeze-substitution.