The localization of four neuropeptidelike substances during embryonic development in amphibian was studied by using immuno cytochemical technique. The cells with positive reaction appeared firstly in the endoderm cells during early tailbud stage, and then were detected in connective tissue at the outer portion of gastrointestinal tract during tadpole stage. In the nervous system, the cells with positive reaction were observed in cranial ganglion and glial cells at the outer margin of the brain and in the inner wall of ventricles. They were also frequently observed in the epidermis during late tailbud stage. The relationship between the appearance of neuropeptides in timespatial sequences and the development of nervous system, the neural crest origin of the cells with positive reaction, and the role of epidermal conductivity in neuropeptidelike cells in epiderms were discussed.
