The neural crest: Its relations with APUD and paraneuron concepts.

Abstract

Abstract. The neural crest cells give rise to a large variety of derivatives including neural, mesenchymal, APUD and/or paraneuron cell types.A better knowledge of these derivatives was partly achieved through studies using LE DOUARIN's quail/chick marker system.We review here evidences which were thus provided for a neural crest origin of calcitonin containing cells, carotid body, aortic paraganglia, adrenomedulla, and against a neurectodermal origin of enterogastric and respiratory tract endocrine cells.The role of neural crest cells in PEARSE's APUD system is discussed. The results implicate that an explanation for the common properties of these cell types and their pathological and biochemical significance should not be looked for in a common embryological origin but at another level.The place of neural crest and, more generally, neurectoderm derivatives in the paraneuron concept of FUJITA is examined. The relevance of the epithelial origin of these cell types to their "receptosecretory" function is stressed.Considering neural crest itself as a unique system is still questioned and discussed here. Its ubiquity and penetration of other systems is pointed out as a widespread phenomenon which is not restricted to APUD and paraneuron systems.The study of the cells which arise from the neural crest received great impetus with the discovery of a new labelling system (LE DOUARIN, 1969, 1973 which was particularly suitable for this type of work. LE DOUARIN and collaborators then undertook a systemic study of neural crest derivatives casting a new light on this long known and somewhat controversial system (cf. reviews by HORsTADIUs,1950, WESTON,1970and LE DOUARIN, 1980. Part of their work dealt with mesectodermal derivatives (LE LIEVRE, 1971 LE LIEVRE and LE DOUARIN, 1975) which have been reviewed in this journal by NAKAMURA (1982). These studies also clarified the role of the neural crest in the formation of the peripheral nervous system (sensory, sympathetic and parasympathetic) (LE DOUARIN and TEILLET, 1971, 1973) and allowed the discovery of the neural crest origin of several other cell types. Currently known neural crest derivatives are listed in Table 1.Some time earlier PEARSE (1966) formulated the APUD concept which gathered