On Nerve Supply, especially, Sensory Nerve Supply of the Lung in Formosan Macaque

Abstract

The fundamental nerve plexus formed in the large bronchial branches of Formosan macaque is much worse developed than that in the human lung, the ganglion found therein being very small both in number and in size. The submucosal plexus of course is very poorly developed, especially so in the submucosa lining the inside of the cartilages and containing not many bronchial glands. The poor development of these plexuses further falls even lower as the bronchial branches ramify into smaller and smaller branches.The nerve plexus found in the intrapulmonary bronchial walls contains a considerable number of medium- and large sized medullated sensory fibres, besides the non-medullated vegetative fibres.The ganglion cells forming the ganglia are not easily classifiable into DOGIEL's Type I and Type II cells, though it is clear that they belong to the sympathicus for they betray multipolarity by their nerve processes. The vegetative fibres in the bronchial branches, as everywhere else, end in STOHR's terminal reticula, which are particularly well developed around the bronchial glands and in the muscularis.More sensory fibres are found in the medium sized than in the large bronchial branches in the lung of Formosan macaque. Of their terminations, mention must be first made of those concerned with the blood pressure falling reflex Type I found in the smooth muscle layer. These terminations are more frequent in the medium-sized bronchial branches with well-developed muscle tissue than in the major branches where the muscle tissue is worse developed. A termination of this type usually originates in an enormously thick fibre and is branched into several thick terminal fibres showing change in size in their courses. Such neurofibrillar expansions, as found in the fibres of terminations of this type in the human lung were absent in my macaque's lung, as in the lungs of dog, goat and bat, as reported hitherto.Besides the above, unbranched and branched sensory terminations were found beneath and in the epithelium of the bronchial branches. Intraepithelial terminations are here more plentiful than subepithelial terminations and, interestingly enough, are particularly abundant in the large bronchial branches. These terminations usually originate in medium-sized fibres, but not rarely, and particularly frequently in the medium-sized bronchial branches, are formed by thick fibres. These terminations are usually more complex in the large than in the medium-sized bronchial branches. Their terminal fibres show little hange in size and those reaching into the epithelium run mostly in winding courses before ending sharply.In the small bronchial branches, the sensory fibres and their terminations are much fewer but branched subepithelial and intraepithelial terminations here are not rare at all. In proportions, however, these are smaller than those seen in the larger bronchial branches, and unbranched terminations are also observed in some places. It is very interesting that the bronchioli smaller than the small bronchial branches are rather rich in sensory fibres and their terminations than the latter. Moreover, very thick fibres are found in the bronchioli ane sensory terminations are sometimes of rather complex type.As in goat, unbranched and simple branched sensory terminations of medium-sized fibres are often found also in the alveolar walls of the lung in Formosan macaque. The terminal fibres of these terminations frequnntly show very perceptible change in size.Small bundles of myelinated sensory fibres are very often found in the pleura visceralis, and the fibres may be sometimes called enormously thick. As the same in bat (NUMATA), these fibres, after losing their myelin sheaths, usually run long widing courses without branching but showing frequent change in size and end in sharp points in the superficial layer of the pleura.