Branches of IMAs (brown, 3,3′-diaminobenzadine stained) run in tight apposition with ICC-IM (blue-gray, c-Kit immuno-labeled with peroxidase). Branches of IMA arrays vary in their degree of varicosity and in the tightness of apposition. (A) Four neighboring principal branches of an IMA array coursing in tight apposition with a network of neighboring ICC-IM intercalated among smooth muscle bundles (unstained). In this example, the IMA branches express modest swellings or varicosities, most of which are in close proximity to the somata and processes of ICC-IM. (B) Two neighboring principal branches of an IMA array course near to, and appear to contact intermittently, the local ICC-IM network. In contrast to the array branches shown in (A), those shown in (B) are more lamelliform, the apparent contacts with the ICC-IM are more intermittent, and many of the IMA lamellae appear to lie on the smooth muscle bundles (unstained) adjacent to the ICC-IM network. (C,D) Two examples of principal IMA branches that course in tight conjunction with ICC-IM and form swellings or varicosities on both ICC-IM somata and fibers. Scale bar = 10 μm. Reproduced with permission from Powley et al. (2016).