Electron microscopical evidence for a direct contact between nerve fibres and mast cells

Abstract

A subungual solitary glomus tumour was examined by both light and electron microscopy. By light microscopy, typical vascularized tumour tissue was seen, surrounded by connective tissue. By electron microscopy, a very close morphological relationship was noted between non-myelinated nerve fibres and mast cells. These mast cells could be divided into two groups: the mast cells of the first group contain numerous mature granules and show few lamellopodia. The distance to the nerve fibre bundles ranged between 2,000 and 20 nm. In the second group, the mast cells always showed direct contact with nerve fibres. They had many lamellopodia and contained almost exclusively immature granules. In some cases, invaginations of lamellpodia and broader cytoplasmatic processes into the axon bundles could be observed. Our findings support the view that mast cells may play an important part in the function of neurons.