Immunocytochemical localization of serotonin in the reptilian lung.

The distribution of serotonin-immunoreactive cells in the lung of 4 species of reptiles was investigated. Serotonin-containing cells were found forming groups in the interconnecting septa in all 4 species studied, and also as solitary cells in Testudo graeca and Mauremys caspica. Serotonin-containing cells were also localized in the intramural ganglia of Pseudemys scripta elegans and Testudo graeca. The present study confirms that serotonin is widely distributed in the lung of vertebrates.