Double labeling of primate intestine sections with patient serum and with commercial antibodies to anti-ITPR1 or ARHGAP26, respectively. The anti-Sj index serum and the commercial antibody to ITPR1 (A) stained both the stratum circulare (SC) and the stratum longitudinale (SL) of the tunica muscularis as well as the muscularis mucosae (MM) and structures adjacent to the enteric villi (V), with a perfect overlay, but spared the plexus myentericus Auerbach (MP), which is located between SC and SL. Conversely, the anti-Ca index serum  and the commercial antibody to ARHGAP26 (B) both stained the MP (and the plexus submucosus Meissner; not shown) but spared the enteric muscle cells. Anti-ITPR1 or anti-ARHGAP26 reactivity is depicted in red (Alexa Fluor® 568), the patient antibody in green (Alexa Fluor® 488), and yellow indicates overlay of the two antibodies. Nuclei are shown in blue (DAPI).