title: Structure of the respiratory tract of the red-bellied newt Cynops pyrrhogaster, with reference to serotonin-positive neuroepithelial endocrine cells.
abstract: To investigate the distribution of serotonin-positive neuroepithelial endocrine (NEE) cells in the respiratory tract of the red-bellied newt Cynops pyrrhogaster, serial sections of the respiratory tract were stained using immunohistochemical methods for serotonin, a periodic acid-Schiff method and hematoxylin-eosin staining. The respiratory tract of the red-bellied newt consisted of a tubular laryngotrachea and two pulmonary sacs. Serotonin-positive solitary NEE cells were distributed widely throughout the ciliomucous epithelium of the laryngotrachea. The innervated clusters of NEE cells, termed neuroepithelial bodies, were rarely found in the caudal portion of the laryngotrachea. The density of NEE cells was high in the middle portion of the laryngotrachea, particularly in the region surrounded by a striated laryngeal sphincter, and the densities were low cranially towards the aditus laryngis and caudally in the pulmonary sacs, the epithelium of which consisted of both ciliomucous epithelial cells and non-ciliated respiratory epithelial cells or pneumocytes. The NEE cells were not observed in the vicinity of non-ciliated respiratory epithelial cells. The morphology and distribution of serotonin-positive NEE cells in the respiratory tract of the red-bellied newt were similar to those described in mammals, including humans. The close localization of NEE cells with ciliary and mucous cells and the distribution of NEE cells in the laryngotrachea suggest that NEE cells play important roles in the defense and repair of the ciliomucous epithelium, such as increasing mucous secretion, ciliary beat frequency and the proliferation of epithelial cells.
authors.affiliation: Department of Anatomy, School of Medicine, Toho University, Tokyo, Japan. naruse@hanada.ac.jp
authors.forename: Hideo
authors.initials: H
authors.lastname: Naruse
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Gomi
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kimura
authors.forename: Dirk
authors.initials: D
authors.lastname: Adriaensen
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Timmermans
mesh_terms: D000818:Animals; D002923:Cilia / Q000502:physiology / Q000648:ultrastructure; D020397:Goblet Cells / Q000166:cytology / Q000378:metabolism; D007150:Immunohistochemistry; D009093:Mucus / Q000378:metabolism; D046569:Neuroepithelial Cells / Q000166:cytology* / Q000378:metabolism; D009490:Neurosecretory Systems / Q000166:cytology* / Q000378:metabolism; D020545:Respiratory Mucosa / Q000166:cytology / Q000378:metabolism; D012137:Respiratory System / Q000166:cytology* / Q000378:metabolism; D012455:Salamandridae / Q000033:anatomy & histology* / Q000502:physiology; D012701:Serotonin / Q000378:metabolism*
chemical_list: D012701:Serotonin