The larynx has three major functions such as protective reflex, respiration and
phonation, and is richly innervated by sensory, sympathetic and parasympathetic nerves. The
sensory innervation of the laryngeal mucosa, which is involved in the perception of pain,
mechanical and chemical irritation, prtects the airway via various laryneal reflexes. We
studied the distribution of Substance P (SP) and Calitonin Gene-Related Peptide (CGRP)
sensory fibers in the rat's larynx using the immuno-histochemical methods.
many SP and CGRP immunoreactive fibers were found in all regions of the laryngeal mucosa
except the vocal cords. SP immunoreactive fibers showed a very similar distribution to the
CGRP fibers in the epithelium and submucosa. But SP immunoreactive fibers were sparser
than CGRP immunoreactive fibers in distribution density. Both reactive fibers were denser in
the supraglottic reactive filbers were denser in the supraglottic region than subglottic region.
Especially, intraepithelial fibers displayed the densest innervation to the laryngeal surface of
the epiglottis. In the subepithelium, SP and CGRP immunoreactive fibers were distributed
along the wall of vessels and around the glands.
The present results suggest that the regional distribution of SP and CGRP immunoreactivity
may be responsible the protective reflex function of the laryngeal inlet.
|