AIM:To study the distribution of nitdc oxide synthese(NOS)in rat stomach myenteric plexus.METHODS:The distribution of NOS in gastric wall wasstudied in quantity and location by the NADPH-diaphorase(NDP)histochemical staining method and whole mountpreperation technique.RESULTS:NOS was distributed in whole stomach wall,mostof them were located In myenteric plexus,and distributed insubmucosal plexus.The shape of NOS positive neuronswas baslcally similar,most of them being round and oval inshape.But their density,size and staining intensity variedgreatly in the different parts of stomach.The density was 62±38 cells/mm~2(antrum),43±32 cells/mm~2(body),and 32±28 cells/mm~2(fundus),respectively.The size andstaining intensity of NOS positive neurons in the funduswere basically the same,the neurons being large and darkstained,while they were obviously different in antrum.Inthe body of the stomach,the NOS positive neurons were inan Intermediate state from fundus to antrum.There weresome beedlike structures which were strung together byNOS positiva varicosities in nerve fibers,some were closelyadherent to the outer walls of blood vessels.CONCLUSION:Nitric oxide might he involved in themodulation of motility,secretion and blood circulation ofthe stomach,and the significant difference of NOS positiveneurons in different parts of stomach myenteric plexus maybe related to the physiologic function of stomach. AIM: To study the distribution of nitdc oxide synthese (NOS) in rat stomach myenteric plexus. METHODS: The distribution of NOS in gastric wall was staged in quantity and location by the NADPH-diaphorase (NDP) histochemical staining method and whole mountpreperation technique .RESULTS : NOS was distributed in whole stomach wall, mostof them were located In myenteric plexus, and distributed insubmucosal plexus. The shape of NOS positive neuronswas baslcally similar, most of them being round and oval inshape.But their density, size and staining intensity variedbly in in the different parts of the stomach. The density was 62 ± 38 cells / mm ~ 2 antrum, 43 ± 32 cells / mm ~ 2 body, and 32 ± 28 cells / mm ~ 2 fundus, respectively. size andstaining intensity of NOS positive neurons in the funduswere basically the same, the neurons being large and darkstained, while they were obviously different in antrum. Inthe body of the stomach, the NOS positive neurons were in Intermediate state from fundus to antrum.There weresome beedl ike structures which were strung together byNOS positiva varicosities in nerve fibers, some were closelyadherent to the outer walls of blood vessels.CONCLUSION: Nitric oxide might he involved in themodulation of motility, secretion and blood circulation of the stomach, and the significant difference of NOS positive nerves in different parts of stomach myenteric plexus maybe related to the physiologic function of stomach