Information regarding the ontogeny and distribution of GIRK channel subunits is crucial to elucidate the contribution of the ion channels to developmental processes and hippocampal functions. Therefore, affinity-purified GIRK subunit-specific antibodies were used to understand how GIRK channel subunit expression develops during postnatal development and becomes organized along the surface of pyramidal cells using histoblotting and immunoelectron microscopy approaches, combined with quantitative analyses.