Development of Argyrophile and Collagenous Fibers in Tissue Cultures. ∗

Abstract

In cultures of adult connective tissue of the rabbit which grow undisturbed on slides or in flasks in the usual plasma and embryonic extract medium for a period of 2 to 3 weeks, development of a fibrous intercellular substance can be observed in the living condition as well as after fixation and staining. In the first stages of this process, extremely delicate loose networks of thin, wavy, branching and anastomosing fibrillae appear around the isolated star shaped fibroblasts which advance into the nutritive medium. The fibrillae are argyrophile, i. e., they are electively impregnated with silver. Although in many places they follow the outlines of the fibroblasts and their processes, and even adhere closely to their protoplasm, the fibrillae are also seen from the very beginning to extend far into the surrounding medium. As the outlines of the fibroblasts are always very distinct, the existence of an exoplasm can be excluded with certainty. The fibrillae sometimes seem to follow the course of the threads of the fibrin network. A direct transformation of the latter into argyrophile fibrillae, however, cannot be proved. (Fig. 1.)

In later stages, which can be observed in the inner areas of the zme of newly formed tissue, the argyrophile fibers become thicker and more numerous, and form dense networks. They continue to adhere to the surface at the fibroblasts, so that the cell bodies often seem to be surrounded by black, basketlike networks. The spaces between the cells are also penetrated by an increasing number of

branching argyrophile fibers connected wit11 the pericellular networks. If epithelial strands are present in the culture, as, for instance, in the cultures of the thymus, dense argyrophile basement inenilxanes appear on the surface of the epithelium.

The branching and interlacing fibrillae gradually become arranged in parallel, longitudinally striated strands or bundles, which stretch in various dirctions and are connected everywhere by looser networks of argyrophile fibrillae.