Morphology of the nerve endings in laryngeal mucosa of the horse

Abstract

Summary To discuss the significance of laryngeal sensation on various disorders of the horse, we studied the morphological and topographical characteristics of sensory structures in the laryngeal mucosa using immunohistochemistry and immunoelectron microscopy. Various sensory structures, i.e. glomerular endings, taste buds and intraepithelial free nerve endings, were found in the laryngeal mucosa by immunohistochemistry for protein gene product 9.5 (PGP 9.5) and neurofilament 200kD (NF200). Glomerular nerve endings were distributed mainly in the epiglottic mucosa; some endings were also found in the arytenoid region arising from thick nerve fibres running through the subepithelial connective tissue. Some terminals directly contacted the epithelial cells. Taste buds were distributed in the epithelium of the epiglottis and aryepiglottic fold. In the whole mount preparation, the taste buds were supplied by the terminal branching of the thick nerve fibres. In some cases, the taste buds were arranged around the opening of the duct of the epiglottic glands. The intraepithelial free nerve endings were found to be immunoreactive for substance P (SP) and calcitonin gene‐related peptide (CGRP). These nerve endings were surrounded by the polygonal stratified epithelial cells in the supraglottic region, and by the ciliated cells in the subglottic region. The density of the intraepithelial free nerve endings was highest in the corniculate process of the arytenoid region and lowest in the vocal cord mucosa. The densities of CGRP‐ and SP‐immunoreactive nerve endings in the arytenoid region were (mean ± s.d.) 30.6 ± 12.0 and 10.0 ± 4.9 per unit epithelial length (1 mm), respectively and in the vocal fold mucosa, 1.1 ± 0.9 and 0.8 ± 0.7, respectively. Approximately one half of the CGRP immunoreactive nerve endings were immunoreactive for SP, and most SP‐immunoreactive nerve endings were also immunoreactive for CGRP. Well‐developed subepithelial plexus with numerous intraepithelial fibres were observed in flat or round mucosal projections that existed on the corniculate process of the arytenoid region. In conclusion, the laryngeal mucosa of the horse seems to have morphology‐ and/or location‐dependent sensory mechanisms against various endo‐and exogenious stimuli.

Morphology and chemical characteristics of subepithelial laminar nerve endings in the rat epiglottic mucosa

“…We re-examined these uncapsulated sensory nerve endings as laminar endings by immunohistochemistry in the dog and rat (Yamamoto et al 1997(Yamamoto et al , 1998(Yamamoto et al , 2000. Although the subepithelial laminar endings were not reported in the horse and humans, subepithelial glomerular nerve endings similar to the laminar endings were reported (Chiba et al 1985;Yamamoto et al 2001). In the larynx, electrophysiological recordings have classified laryngeal sensory receptors into several types based on specific stimulants, namely, acidity, touch, airflow, luminal pressure changes and chemical substances (Sant'Ambrogio et al 1983;Sekizawa and Tsubone 1991).…”

Gross anatomy of the nose, nasal cavity and larynx in the pampas deer (Ozotoceros bezoarticus, Linnaeus 1758)

“…In mammals, the great diversity of habitats and social systems has led to the evolution of a great variety of vocal tract specializations. Some studies (Bisaillon, 1985, Frey and Gebler, 2003, Frey et al, 2006, Frey et al, 2007a (Harrison, 1980, Frey and Gebler, 2003, Frey et al, 2006Frey et al, 2007a, b) and the taste buds of the larynx (Bradley et al, 1980;Yamamoto et al, 2001).…”

3D kinematic of the thoracolumbar spine in Mangalarga Marchador horses performing the marcha batida gait and being led by hand—A preliminary report

“…Many in-vitro cadaveric studies have examined the mobility of the equine spine [ 10 – 13 ], and numerous in-vivo studies have investigated the mobility of the back in the trot [ 14 – 17 ]. However, no study has analyzed this movement in the marcha batida gait, which is the natural gait of many horses such as the MM, and today it is the gait most used in Brazilian gaited competitions.…”