STUDY ON ULTRASTRUCTURE OF THE FIBROBLASTS / 解剖学报

ABSTRACT

Male Wistar rats were used to investigate the ultrastructure of the fibroblasts. The animals were sacrified at several time intervals after the collodion tubules were embedded subscutaneously on the backs, and the materials taken from the connective tissues around the collodion tubules were observed by light and electron microscopy. Six basic types of fibroblasts (little-differentiated fibroblast, young fibroblast, collagenoblast, myofibroblast, fibroclast and fibrocyte) were studied ultrastructurally. In each of its three phases (prophase, metaphase and telophase), the collagenoblast showed different functional conditions. The fibroclasts contain two subtypes, the phagocytosis and the lysosome subtypes, the former phagocytosing the collagen fibrils with a characteristic crossing banding and the latter phagocytosing the collagen fibrils which had been cleaved by the collagenase. The fibrocytes consist probably of two subtypes, the resting and aging subtypes. The observations demonstrate that the fibroblasts were derived from undifferentiated cells around capillaries and the little-differentiated fibroblasts are the youngest cell type of all fibroblasts. The collagenoblasts and fibroclasts are the main cells responsible for collagen biosynthesis and collagen degradation respectively. In the present paper a new concept, the "The Fibroblast System", has been proposed, which includes the six basic types of fibroblasts and there are not only structural but also functional relationships among them.