Serial Section Radioautography of the Inner Ear: Histological Technique

THE FOLLOWING histological technique was developed in order to obtain routine serial sections of mouse temporal bones of a quality suitable for optimal light microscopy and radioautography. Light microscopic radioautography with tritium requires that sections be cut no thicker than 10μ and that they lie flat on the slide. These criteria are not readily met in the case of the heterogeneous tissues of the inner ear. A double embedding technique¹ was discarded because too long a time was required. Paraffin embedding, used by other investigators,^2-4 has resulted in poor cytological detail and artifacts in the radioautographs. Frozen sections of tissues embedded with polyvinylpyrrolidone (PVP) or gelatin were studied but the sections did not lie flat, it was difficult to obtain serial sections, and the cochlea sections usually fragmented. The method to be described is similar to one reported earlier,⁵ but with modifications that were found helpful in