Scanning electron microscopy of the normal and denervated limb regenerate in the newt, Notophthalmus, including observations on embryonic amphibia limb-bud mesenchyme and blastemas of fish-fin regenerates.

The present work deals with the morphology of normal and denervated early limb regenerates in the newt and compares them with early limb-bud mesenchyme and blastemas of fish-fin regenerates using the three-dimensional properties of the SEM. It shows that blastemal cells are polymorphic, in contrast to those of the stump-cell population, which are fairly homogeneous and from which blastema cells are said to arise by "dedifferentiation." The appearance of cells had not changed by two days following denervation even though previous biochemical studies have detected many changes in metabolism. Longterm denervation (7 days) did result in morphological changes. A comparison between well-known cell types-myoblasts, Schwann cells, osteoblasts observed in vitro, limb-bud mesenchyme and mesenchymatous fin blastema-was carried out in order to suggest explanations for the blastema-cell polymorphism.