Receptors by MOS promotes reconstruction of an enteric neural circuit injured after the surgery as has been demonstrated in the lower gut. In mice treated with the 5-HT4 antagonist, SB 207266 plus MOS solution for 1 week after anastomosis, no neurons or nerve fibers were observed in the anastomotic region, although aggregates of small cells were observed near the surface. Thus, enteric neurogenesis was largely suppressed by simultaneous administration of the 5HT4 receptor blocker, SB along with MOS. Similar results were obtained with all 4 mice treated with MOS and SB. Using confocal imaging of fixed, whole mount preparations, no nerve cells or fibers were visible in the granulation AbMole Nitisinone tissue at the anastomosis, although intact myenteric plexus was visible in the intact area in a mouse treated with SB and MOS solution for 1 week after surgery. The average number of neurons observed amongst nine fields within the anastomosis in mice treated with MOS solution was significantly larger than that in SB plus MOS treated mice or DMSO-treated mice after anastomosis. New neurons were observed without oral or anal and mesenteric or anti-mesenteric localizations in any of the three groups. This is the first study involving in vivo imaging of enteric neurons with 2PM, although in vivo imaging of enteric neurons with confocal laser AbMole Octinoxate endomicroscopy has been recently performed. We detected the formation of newly generated neurons in the thick granulation tissue at the site of anastomosis. Imaging with 2 PM allowed enteric neural imaging several hundred microns deep within the gut of living mouse. In contrast to the brain tissue, the structure of the gut tissue is complex, consisting of multiple layers and tissue types, including mucosa, submucosa, circular and longitudinal muscles, blood vessels and crypt glands. Therefore, to enhance visualization of enteric neurons we used Thy1-GFP mice after confirmation of expression of cytoplasmic GFP in enteric neurons in preliminary studies. In the present study, newly formed enteric neurons also expressed cytoplasmic GFP. In future studies, we are planning functional studies of enteric neurons using in vivo imaging with 2PM and genetically encoding calcium indicators. A critical obstacle to overcome in order to obtain clear images of enteric neurons in vivo was to suppress motion disturbance associated with gut motility. Otherwise, observed images would be blurry and non-interpretable. We found that pinning and intraluminal injection of papaverine eliminated tissue movement and allowed for the acquisition of sharp images. One week after surgical anastomosis, MOS facilitated formation of newly generated enteric neurons in the granulation tissue at the anastomosis. However, even 4 weeks after surgery, only a small number of newborn neurons were identified in the granulation tissue of vehicle-treated control animals. The effects of MOS on neurogenesis were completely antagonized by treatment with a 5HT4 receptor antagonist, indicating that MOS facilitated formation of newborn enteric neurons via 5-HT4-receptor activation. Although the number of newly formed enteric neurons was significantly higher in the MOS-treated mice as compared to antagonist treated and vehicle controls, the distribution pattern of newly formed enteric neurons was similar, i.e., neurons were distributed close to the edge of the granulation tissue. This suggested the possibility that neural stem cells were mobilized from the outside of the granulation tissue.