Chlorphentermine-induced changes of the peripheral vestibular sense organ of the rat.

Chronic feeding of chlorphentermine to young rats induces an accumulation of electron dense conglomerates and vacuoles in intraepithelial afferent nerve fibres of maculae and cristae in the vestibular part of the inner ear. In spite of the fact that preterminal parts of axons are severely swollen due to this accumulation, the nerve terminals maintain their normal size but can sometimes contain inclusions. Efferent fibres always remain free of these changes. Sensory cells, vestibular ganglion cells and occasionally supporting cells contain lamellar and crystalloid-like inclusions which disappear when the treatment is interrupted. After a long-term feeding break the nerve fibre inclusions disappear. A few swollen distended morphologically empty preterminals remain. The preference of inclusion body accumulation in afferent neurons may indicate an especially high lipid turnover in this part of the hair cell innervation.