Immunohistochemical Localization Of5-HT And Its Synthesizing Enzyme TPH In Hydra. Fusca

In this study, we used the Colophony-Paraffin embedded section technique, combined with the Streptavidin-Peroxidase immunohistochemical method to located5-HT and TPH immunoreactive cells in the nerve system of Hydra. fusca. Hydra have endoderm and ectoderm, who were separated by a gelatinous mesoglea. In the two cell layers, the mainly cells are epithelio-muscular cell、sensory cells、intercalated cells、nerve cells and nematocyst. Our research found that the cell layers of hydra had significant regional characteristics in structure, for example:body column area I had more types of cells than area II, and endoderm of area I was much more tightness; ectoderm of area I has shorter cell layers. Form the immunohistochemical results we found that most Hydra. fusca bodies showed strong5-HT immunoreaction, and had stable reaction pattern. All immunoreaction occured in endoderm and along the outer layer of mesoglea. Hydra. fusca also showed strong immunoreaction of TPH polyclonal antibody, and the response pattern consistent with5-HT. In this study, we successfully marked many5-HT/TPH immune-positive sensory cells, nerve cells and nematocyst. Those positive cells mainly located in the base of endoderm of body column area, with flat oval or triangles mall cell bodies. The marked positive nerve cells were mainly biopolar, with short fibers extended towards the two poles of cells; The base of the positive sense cells submit projection and connected to the neural process of the nerve cells; Nematocyst relatively concentrated in the tentacles, and strongly react, positive cells were dark brown.The research results showed that there was specific TPH of the vertebrate in the coelenterate Hydra. fusca. TPH controls the product of5-HT in the nervous system. And the results also revealed TPH and PAH function differentiation happened before coelenterate at least.5-HT, as a neurotransmitter involved in the movement of hydra, and it may be associated with the release of toxins in nematocyst..