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.