Statoconia displacement in squirrel monkey ears.

When findings in squirrel monkey temporal bones after streptomycin sulfate intoxication were compared with those after application of intense linear acceleration, the dislocated utricular statoconia were more frequently found around the cupula of the crista ampullaris posterior in the latter group, whereas statoconia were rather widely disseminated within three semicircular canals (cupula, ampulla, and duct) after streptomycin intoxication. This difference is most probably due to the fact that, in the linear acceleration group, normal statoconia were instantaneously dislodged in a block (or forming a large-sized mass) and thereafter moved in the gravity direction, whereas in the streptomycin group, degenerated statoconia formed smaller groups and were more freely disseminated. In the endolymphatic sac, dislocated statoconia were readily phagocytosed by the epithelium of the intermediate portion and rugous portion (and transitory portion). The incidence of phagocytosis was found more in the streptomycin group, compared to the linear acceleration group.