Anomalous Development of Otoliths Associated with Postural Defects in Manganese-deficient Guinea Pigs

The high incidence of abnormal head movements observed in manganese-deficient guinea pigs at birth has led to a study of structural and histochemical differences in portions of the ear of deficient and control animals. Oil of wintergreen preparations of the ear have been made and have revealed the failure of otolith development in the utricular and saccular maculae in manganese-deficient young. Post-natal supplementation with manganese has not reversed the symptoms of vestibular disturbances and supplemented animals have always shown the existence of unilateral or bilateral defects of the otoliths. A smaller proportion of the deficient animals have in addition abnormal curvatures of the semicircular canals and misshapen ampullae. Macular preparations of the ears were stained with metachromatic techniques to estimate the concentration of acid mucopolysaccharides present. Positive tests for AMPS were observed only in normal otolithic. These studies are a continuation of an investigation of the importance of manganese in AMPS synthesis and suggest that the defects of motion observed in deficient guinea pigs are brought about by faulty otolith development influenced by limitations in AMPS synthesis in the presence of manganese deficiency during fetal development.