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.

Light microscopic and immunohistochemical study of the trachea of the broad-snouted caiman (Caiman latirostris)

“…However, the tracheal cells of Pseudemys scripta elegans were positive only to PAS and AB pH 2.5 (Pastor et al, 1987a). According to Naruse et al (2005), the cilia and mucous secreted by goblet cells in the epithelium represent the first line of airway defence after exposure to infection, pollution, toxins or inflammation.…”

“…Serotonin immunoreactive cells in the respiratory system may possibly play an important role in the defense and repair of the ciliomucous epithelium, such as increasing mucus secretion, ciliary beat frequency and proliferation of epithelial cells (Naruse et al, 2005).…”

Extensive presence of serotonergic cells and fibers in the peripheral nervous system of lampreys

“…The present results show that there is a close relation between these cells and the FSCs of the pharyngeal groves and gill seam. Studies carried out in echinoderms (Wada et al,1997), gastropods (Diefenbach et al,1991; McKenzie et al,1998; Uhler et al,2000; Doran et al,2004; Braubach et al,2006), mollusks (Pavlova et al,1999; Kuang and Goldberg,2001; Koss et al,2003), and amphibians (Maruyama et al,1984a,b; Naruse et al,2005) showed that 5‐HT plays a key role in the control of mucus secretion and ciliary beat frequency. The close relation between 5‐HT‐ir FSCs and the ciliated and mucous epithelia observed in lamprey may indicate that these cells are also involved in the control of the ciliary beat and mucus secretion.…”

Localizations of cells that secrete bombesin, glucagon, somatostatin-14 in stomach (proventriculus and gizzard) in chicken (Gallus gallus domestica L.) during the prenatal and postnatal periods

“…In recent years, DNES (Diffuse Neuro Endocrine System) has taken place of APUD (14,19,20,35). The systems which are constitued by these cells are called gastroenteropancreatic (GEP) system or gastroenteropancreatic-neuroendocrine system (1,13,20,22,35).…”