The endolymphatic surface of the stria vascularis in the guinea-pig and the effects of ethacrynic acid as shown by scanning electron microscopy.

Examination of the endolymphatic surface of the stria vascularis showed, in agreement with previous studies, the marginal cells to be hexagonal in shape and that most possessed microvilli. However, the cells in the apical turns were more profusely covered with microvilli than those at the base and, particularly in the basal turns, there was some variation in the surface detail of the cells. These results may indicate differences in the physiological state of the cells. In the early period of ethacrynic acid intoxication (15-30 minutes post-injection), when rapid changes in endolymphatic potential and ion-fluxes occur, the surface of the marginal cells showed only slight distortion. The most dramatic changes were noted 1 hour post-injection, and involved swelling of the cells and loss of microvilli. This distortion persisted up to 2 hours post-injection. The possible explanation for these findings is discussed.