mRNA encoding the 5-HT2B receptor is expressed in intestinal neurons. In situ hybridization with an 35S-riboprobe. A, Rat colon (antisense riboprobe). mRNA encoding the 5-HT2B receptor is concentrated in cells in the myenteric ganglia. B, Rat colon, control (sense riboprobe). C, E, Mouse ileum sections (antisense riboprobe). mRNA encoding the 5-HT2Breceptor is found in crypt epithelial cells (→). D, F,Mouse ileum sections, control (sense riboprobe). L, Lumen. Scale bars: A–D, 50 μm; E, F, 20 μm.