Neural Crest Derivatives
Neurofilaments or GFAP have been detected in Schwann cells and neurons derived from the neural crest (Yen and Fields 1981; Barber and Lindsey 1982; for review see Achtstaetter et al. 1986). It is still not known whether any other neuronal crest derivative in adult tissues is able to express cytokeratins, excepting the arachnoidal cells and the corneal endothelium (see Chap. 8; Zwaan and Webster 1985; Shamsuddin et al. 1986; Kasper et al. 1992b). Furthermore, the Merkel’s cells of the skin express cytokeratins, but there is controversy regarding their neural crest origin (I. Moll et al. 1990). The adrenal medulla lacks cytokeratins (Miettinen et al. 1985b).