Figure 5.

Distinct morphological and neurochemical subtypes of inhibitory IM neurons. A, B, Morphologically-distinct aspiny (red, stained with CB) and spiny (green, stained with DARPP-32) IM neurons. C, The three distinct neurochemical subtypes of IM neurons and their relative proportion in the rhesus monkey IM. Note that all spiny neurons in IM were DARPP-32+ and about a third of them were also CB+. Aspiny IM neurons belonged to two classes: those that were CB+ and those that were NOS/NADPHd+. The IM neuron breakdown shown in the bar plots was as follows (mean ± SEM): 63 ± 3% (spiny DARPP-32; a third of these spiny DARPP-32+ neurons also co-expressed CB) + 23 ± 7% (aspiny CB+) + 14 ± 2% (aspiny NOS+). D–G, Nisslstained neurons and glia in IM. H–L, Nissl-counterstained neurons in IM, also labeled for DARPP-32 (H–J), NOS (K), and CB (L), shown as brown DAB precipitate. Different arrows in D–L indicate all identified cell types, based on the size of their cell body, the presence or paucity of stained cytoplasm, size of nucleus, and the presence of one clearly defined nucleolus or multiple heterochromatin clumps, as follows: Black arrows: Large/medium neurons with one clearly defined nucleolus; Orange arrows: Small neurons with multiple heterochromatin clumps; Green arrowheads: Astrocytes, no visible cytoplasm and multiple heterochromatin clumps; Black arrowheads: Microglia, no visible cytoplasm, darkly stained and irregularly-shaped nucleus; White and black, silhouette arrowheads: Oligodendrocytes, no visible cytoplasm, darkly stained and oval or round-shaped nucleus with one to four thick heterochromatin clumps situated under the nuclear envelope (note number of heterochromatin clumps in panel G with lightly stained glial cells, resembling overexposure and high dynamic range during live imaging). Scale bar in B applies to A and B.