Type I calretinin interneurons were found at highest density in the most dorsal rostral pole of the normal mouse striatum. These unusual-looking neurons had small-medium sized somata and were usually unipolar with sparsely spiny porly branched dendrites. In NPY-cre mice, these neurons were seen to make elicit IPSCs in nearby spiny neurons. Tepper and Koós, (2017) and Shah and Tepper, unpublished.
Type II calretinin interneurons were found throughout the mouse striatum except at the rostral pole. These neurons were characterized by 2-4 thick, smooth primary dendrites that branched into a sparse, non-varicose dendritic arborization that extended for several hundred micorometers from the soma. Tepper and Koós, (2017) and Shah and Tepper, unpublished.
Type III calretinin interneurons were found mostly in the middle and caudal regions of the mouse striatum. These neurons were characterized by 3-5 thin, varicose primary dendrites that branched more extensively into a compact dendritic arborization that extended only for a few hundred micorometers from the soma. These neurons were often seen in a brightly stained region of the neuropil that may represent a dense local axonal arborization. Tepper and Koós, (2017) and Shah and Tepper, unpublished.
Calretinin interneurons are often clustered at the boundary between striatum and GP. Shah and Tepper (unpublished).