On innervation of mucous membrane of larynx in canine fetus.

Abstract

The development of sensory nerve fibres in the mucous membrane of larynx of canine fetus in the last stage is weaker than that in grownup dog, but the distribution is much the same, being richest on the laryngeal side of epiglottis and poorest in pars intermembranacea and ventriculus laryngis. No formation of sensory terminations related with Hering's blood pressure falling reflex has been observed, neither of Type I nor Type II. These are presumed to be formed gradually after birth. The sensory terminations are in general represented by unbranched and simple branched terminations. Some of them frequently pass into intraepithelial fibres which are especially well-developed on the laryngeal side of epiglottis, so as to compare favorably with those in adult dog. The formation of taste-buds in larynx is not much different from that in adult dog, no noteworthy difference existing between the developments of the sensory fibres to the taste-buds of fetal and adult dogs. However, their terminations are in fetus generally simpler than in adult in structure, intra- and extragemmal fibres being found only rarely.