Effects of chronic denervation in type I cutaneous mechanoreceptors (Haarscheiben)

Cutaneous type I receptor sites (Haarscheiben or tactile domes) were examined at intervals of 4 to 275 days after chronic denervation of the skin. The number of domes decreased with denervation time, and only about one-third of the domes originally present were still visible at 275 days. Most but not all of the Merkel cells from these domes were absent by 48 days, and the epithelium was significantly thinner than in nondenervated domes. Only a few of the examined domes appeared to be completely devoid of Merkel cells. It is concluded that after nerve transection, domes degenerate but do not always disappear entirely. The remnants may thus act as target sites which either attract regenerating type I nerve fibers or facilitate the formation of new dome structures after nerve regeneration.