High resolution radioautographic study of the inner ear following in vivo tritiated deoxyglucose administration

Light and high resolution radioautography were performed on cat and guinea pig inner ear after an in vivo administration of tritiated deoxyglucose and conventional histological treatments. In the guinea pig cochlea a diffuse radioautographic reaction product appeared on all the neurosensory and surrounding structures, with a more intense labelling of stria vascularis and Reissner's membrane. In the cat vestibular organ a diffuse reaction was also noted, with an intense clear-cut labelling of some dark cells at the base of the lateral crista and on some cells limiting the endolymphatic space, opposite the utricular macula. At the EM level, the silver grain distribution preferentially appeared to be localized on the cytoplasmic glycogen granules. In addition, some sensory cells were densely marked, the silver grains neither occurring on the nucleus nor on the surrounding nerve calyx, and rarely upon the mitochondria. These data indicate that using classical histological treatments, it is possible to retain a part of the radioactive molecules around the injection site. The possible physiological meaning of the selective labeling of some cellular and subcellular compartments is discussed.