The ultrastructure of cutaneous type I mechanoreceptors (Haarscheiben) in cats following denervation

Abstract

Denervation of specialized cutaneous mechanoreceptors (Haarscheiben or domes) in cats was followed after 20 and 25 days by the following alterations in receptor structure: (1) reduced numbers of Merkel cells, (2) Merkel cells degenerating in situ, (3) fewer dense-core granules in the cytoplasm of Merkel cells, (4) an increased number of agranular dendritic cells and Langerhans cells in the dome, (5) the apparent phagocytosis of Merkel cells by Schwann and Langerhans cells, (6) fewer epithelial cell layers over the dome, and (7) a decrease in the number of transitional cells. Skin excised between the domes in the denervated nerve field appeared normal when compared to innervated skin, and it was considered unlikely that the alterations in dome structure were due to generalized nutritional changes in the skin caused by transection of sympathetic axons or to some other side effect of denervation. Since domes are formed in new locations on the skin after nerves have regenerated (Burgess et al., '74), changes in dome structure following nerve transection are probably due to loss of the "trophic" influence of the nerves supplying the dome.

Merkel cell development in the wound healing in the labial mucosa of adult rabbits.

“…A lot of papers on the Merkel cell have appeared during the last two decades (CAUNNA, 1962;MUNGER, 1965MUNGER, , 1977MUSTAKALLIO and KIISTALA, 1967;SMITH, 1967SMITH, , 1970IGGO and MUIR, 1969;KUROSUMI et al, 1969;BREATHNACH, 1971;LYNE and HOLLIS 1971;HASHIMOTO, 1972 a, b;ANDRES and DURING, 1973;NAFSTAD, 1971a, b;WINKELMANN and BREATHNACH, 1973;ENGLISH, 1974ENGLISH, , 1977WHEITEAR, 1974;BUDTZ and LARSEN, 1975;HALATA, 1975;SAXOD, 1978;TWEEDLE, 1978;TACHIBANA, 1978TACHIBANA, , 1979, and many others). But the life history, including the developmental origin, of the Merkel cell is not necessarily clear.…”

Primary Neuroendocrine (Merkel Cell) Carcinoma of the Anterior Skull Base

“…Since the first description of Merkel Cell carcinoma as a sweat gland carcinoma by Toker in 1972 and the identification of neurosecretory granules by electron microscopy 25 confirming the neuroendocrine origin of the tumor, this neoplasm has been characterized in detail 1,4,15,20,21,23,26,27. The nearly exclusive appearence as primary skin tumor most common in the head and neck region (54%) followed by the lower limbs (27%) and the arms and trunk (19%) 12 is due to the distribution of the postulated cell of origin, the cutaneous Merkel cell 1,4.5,20,22,26 Although Merkel cells are also described to be present in the oral mucosa 6 the palate 29, only a few reports of Merkel cell carcinomas locations other than the skin have been published in recent years 9,14,17, 30.…”

An experimental study of the influence of sensory nerve fibers on Merkel cell differentiation in the labial mucosa of the rabbits.

“…Part of the lower labial mucosa was excised following mental nerve resection. (ENGLISH, 1974;OCHIAI, 1977;OCHIAI et al, 1979;TACHIBANA, 1979;ENGLISH et al, 1980;OCHIAI and SuzuKI, 1981;TACHIBANA and ISHIZEKI, 1981). However, the mechanism of differentiation of the Merkel cell is unknown.…”

“…Some authors have shown that very little change occurred in the number and ultrastructure of Merkel cells after denervation (SMITH, 1966(SMITH, , 1967HARTSCHUH and WEIHE, 1977;BENKENSTEIN, 1979;TACHIBANA et al, 1982). On the other hand, other authors (PALMER, 1965;BURGESS et al, 1974;ENGLISH, 1977;KUROSUMI et al, 1979) have shown or suggested a marked decrease in the number of Merkel cells and the specific granules in Merkel cell following denervation, and elicited a supposition that some neurotrophic influence exists between the Merkel cell and the nerve terminal.…”