Expression of P2X1 receptors and SOM in the myenteric plexus of the mouse gastrointestinal tract. a–d P2X1 receptor-ir in stomach corpus, jejunum, ileum and distal colon, respectively. e–h are SOM-ir in the same regions of a–d, respectively. i–l The merged images of a and e, b and f, c and g, and d and h, respectively. Note that the scattered P2X1 receptor-ir neurons were all labeled with SOM-ir. All the scale bars = 60 μm