Light microscopic immunoenzyme and electron microscopic immunogold cytochemistry reveal tachykinin immunoreactivity in Merkel cells of pig skin.
Light microscopic (LM) immunoenzyme and electron microscopic (EM) immunogold cytochemistry were used to demonstrate the presence and subcellular distribution of tachykinin (substance P)-like immunoreactivity in Merkel cells of pig skin. Merkel cells of sinus hair follicles were strongly immunoreactive for tachykinins. In contrast, tachykinin-like immunoreactivity was absent from or very weak in epidermal Merkel cells while subepidermal and some intraepidermal nerve fibres were clearly immunopositive for tachykinins. Postembedding immunogold cytochemistry on the EM level revealed that tachykinin-like immunoreactivity was confined to the secretory granules in Merkel cells. Tachykinin immunoreactivity was clearly absent from the axon of the Merkel cell-axon complex. The selective presence of tachykinin immunoreactivity in secretory granules strongly suggests that tachykinins are synthesized in cutaneous Merkel cells, at least of pig. This is a further indication for the concept that the Merkel cell is a member of the diffuse neuroendocrine system. However, the functional role of tachykinins like substance P and neurokinin A and of other peptides present in Merkel cells remains enigmatic.
Weihe
E
E
Department of Anatomy, Johannes Gutenberg-University Mainz, F.R.G.
Hartschuh
W
W
Nohr
D
D
D000818:Animals; D006651:Histocytochemistry; D007124:Immunoenzyme Techniques; D007150:Immunohistochemistry; D008853:Microscopy; D008854:Microscopy, Electron; D012867:Skin / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D013552:Swine; D015320:Tachykinins / Q000276:immunology / Q000378:metabolism*
D015320:Tachykinins