Structural and Endocytotic Differences of Fibroblasts and Macrophages in the Tail Fin of Amphibian Larvae during Metamorphosis

Abstract

Different features in the fibroblasts and the macrophages, which are prominent cell types in the dermis of the dorsal tail fin of the larval axolotl, Ambystoma mexicanum, and the tadpole, Rana japonica, were examined by light andelectron microscopy. At the non-metamorphic stages, the cytoplasm of the macrophage, loaded with numerous lysosomes, is generally located in the cell periphery. Outstanding was the presence of many ruffles or microvillous projections ofdifferent shapes and sizes in the plasma membrane. In contrast, the fibroblasts are spindle-shaped and possess less numerous microvillous projections compared with the macrophages, and extracellular spaces neighboring the fibroblasts are loaded with collagen fibers. The fibroblasts are located superficially and sometimes contact each other by the desmosomes. The macrophages are situated relatively deep in the dermis. © 1992, International Society of Histology and Cytology. All rights reserved.