Morphological study of the intrapharyngeal ganglia and ganglionic neurons in cats

Intrinsic neuroendocrine cells in the outer wall of the human pyriform recess

The extrinsic neural supply of the hypopharynx is well established. However, little is known about the intrinsic neurons and neuroendocrine cells (NECs) of the human hypopharynx that are under the influence of the extrinsic nerves. We aimed to identify and characterize such cell populations within the outer wall of the pyriform recess. We applied antibodies for neuron-specific enolase (NSE), calretinin (CR) and neurofilaments (NF) to autopsy samples from four donor cadavers. Within the lamina propria and the muscle layer of the pyriform recess outer wall, usually in perivascular areas, we found NSE-, CR- and NF-positive cells, mostly apolar, that were considered on a histological and immunohistochemical basis to be NECs. Although these cells have not, to our knowledge, been described previously in this anatomical location, their presence within the hypopharynx wall may explain the appearance of rare forms of local primary neuroendocrine carcinomas.

Extending the enteric nervous system

The work reviews the evidence suggesting that lingual components of the autonomic system may be considered the most rostral portion of the enteric nervous system (ENS) defining the concept of lingual ENS (LENS). The LENS is not dissimilar from the more distally located portions of the ENS, however, it is characterized by a massive sensory input generated by collaterals of gustatory and trigeminal fibers. The different neuronal subpopulations that compose the LENS operate reflexes involved in regulation of secretion and vasomotility. Systemic reflexes on the digestive and respiratory apparatus are operated by means of neural connections through the pharynx or larynx. The LENS can modulate the activity of distally located organs by means of the annexed glands.The LENS seems therefore to be a "chemical eye" located at the beginning of the digestive apparatus which analyses the foods before their ingestion and diffuses this information distally. The definition of the LENS supports the concept of an elevated degree of autonomy in the ENS and puts in a new light the role of the gustatory system in modulation of the digestive functions. For its characteristics, the LENS appears to be an ideal model to study the elementary connectivity of the ENS.

Adrenergic and acetylcholinesterase-positive innervation of palatine tonsils in mammals

Innervation of human, feline and rabbit palatine tonsils was investigated. Adrenergic nerve components were visualized by formaldehyde-induced fluorescence of catecholamines and 5-HT, or by glyoxylic acid fluorescence, whereas acetylcholinesterase (AChE)-positive nerve structures were demonstrated by the direct thiocholine method. The largest density of adrenergic and AChE-positive nerve profiles was found in the adventitia of arterial branches in the fibrous capsula and septa, mainly in the form of periarterial nerve plexuses of different density. Fine nerve fibres lined the wall of small arteries which penetrated into extrafollicular lymphoid tissue and marginal layers of follicles. It is concluded that there are significant species-specific differences related to density, nature and topographic relations of adrenergic and AChE-positive nerve fibres in the various structural parts of palatine tonsils.

Sensory innervation of the pharynx and larynx

To shed light on supraesophageal complications of reflux disease, sensory innervation--particularly, distinct distribution, area, and density of sensory fibers--of the feline pharyngolaryngeal mucosa was reported. The investigations were performed by means of histochemistry (tracer techniques) and immunohistochemistry. The pharyngeal mucosa from the Eustachian cushion to the middle level of aryepiglottic fold, except the laryngeal surface of epiglottis, was supplied by the glossopharyngeal sensory fibers, whereas the laryngeal sensory fibers innervated between the apex of epiglottis and the level of the first tracheal ring in the larynx and between the middle level of aryepiglottic fold and the caudal end of piriform sinus in the pharynx. Most areas of the mucosa, except the subglottis, had unilateral innervation. The subglottis, including the caudal aspect of vocal fold and the posterior glottis, had bilateral supply with ipsilateral predominance. The density of sensory fibers in the vestibule of larynx involving the posterolateral aspect of arytenoid eminence was much heavier than the other parts. Sensory nerve fibers around the caudal pole of palatine tonsil, and in the root of tongue and the hypopharyngeal wall also were dense. Regional distribution and density of substance P and calcitonin gene-related peptide immunoreactive fibers showed almost the same pattern as did the sensory fibers.