Frozen-section autoradiography of the cochlea: evidence for differential distribution of amino acids.

A histological method is described for embedding the whole cochlea in an egg yolk medium that permits frozen sectioning in the mid-modiolar plane. Resulting tissues can be processed using standard autoradiographic techniques and stained with Nissl or silver impregnation methods. Following identical intracochlear injections of tritiated proline or leucine and frozen sectioning of embedded cochleae, differential uptake patterns within the cochlea were revealed for these amino acids. Frozen sectioning of the cochlea promises to provide an efficient means to examine specific labeling patterns within the cochlear duct for compounds suspected of contributing to cochlear function by permitting the application of multiple histological techniques including routine stains and anterograde and retrograde tracers.