[Distribution of 5-hydroxytryptamine immunostaining cells in various tissues of Bufo bufo gargarizans]

The distribution of 5-hydroxytryptamine (5-HT) immunostaining cells in the digestive tracts (hibernation and nonhibernation), the brain and other various tissues of Bufo bufo gargarizans was studied by peroxidase anti-peroxidase immunocytochemical method. In the brain, 5-HT immunostaining cells were localized in the raphen nuclear area of brain stem and in the ependyma cell area of the ventriclus tertius of diencephalon. These immunostaining cells were round or oval. The cells usually possess processes which were filled with immunoreactive substance. Some of the processes were contact with the processes of other cells. A few 5-HT positive reactive nerve fibers were observed in the brain stem and the diencephalon. The density of 5-HT immunostaining cells in the digestive tubes were the highest in the pylorus, fundus, cardia of gaster, and moderate in the esophagus and duodenum and the lowest in the large intestine and the small intestine. The density of 5-HT immunostaining cells in the digestive tubes were higher in nonhibernant toads than in hibernant toads. By the statistical method, the difference of the density between the two sorts of toads were notable (P less than 0.05). The 5-HT immunostaining cells were visualized to distribute between the epithelium cells of the mucosa or the epithelium cells of gland. These positive cells usually had one or more processes which contained 5-HT immunoreactive substance. Some were reached into lumen surface of the gland or intestine. Some were extended into lamina propria through the basal membrane. These results indicate that the 5-HT immunostaining cells in digestive tubes could release 5-HT by both endocrine and exocrine ways.