IMMUNOELECTRONMICROSCOPIC LOCALIZATION OF SYNAPTOPHYSIN IN THE ORGAN OF CORTI OF THE GUINEA-PIG

Synaptophysin has been localized previously in the mammalian cochlea a t the light-microscopic level and in few reports by electron microscop y using either a preincubation procedure or the avidin-biotin reaction . Here we present results of the electron-microscopic analysis for pos tembedding immunoreactivity of synaptophysin in the cochlea of the gui nea pig of LR-White-embedded samples. Strong synaptophysin immunoreact ivity is located in the cytoplasm of the efferent nerve endings at the base of inner and outer hair cells. Besides this, some antibodies to synaptophysin were also identified in the cytoplasm of outer hair cell s. To get more information about the cellular content of synaptophysin , the density of the immunoreaction per square micrometer was determin ed for the outer hair cells of the second turn of the cochlea counting the gold particles in numerous ultrathin sections. The role of synapt ophysin identified in the cytoplasm of outer hair cells is discussed.