Abstract
We describe a new technique for the morphological characterization of immunohistochemically labeled neuron populations. We demonstrate that it is possible to fill neurons iontophoretically with Lucifer Yellow (LY) in fixed slices of cat visual cortex after the respective cells have been identified by indirect immunofluorescence for the neural cell adhesion molecule N-CAM 180, with the VC1.1 antibody or with an antibody against glutamate dehydrogenase (GAD). Morphological analysis of the injected cells at the light and electron microscopic level revealed that the N-CAM 180-positive neurons share the features of neuropeptidergic cortical interneurons. Depending on the antibody applied, the immunohistochemical treatment had little or no noticeable effect on the quality of LY filling or on the preservation of morphological details of the pre-labeled cells. This makes the method described ideally suited for the light and electron microscopic examination of selected, immunologically characterized neuron subpopulations.