Studies on the Growth of Tissues in Vitro

Abstract

ABSTRACT In a previous paper of this series (Trowell & Willmer, 1939) an account was given of the effects on the growth of chick periosteal fibroblasts of the addition of saline extracts of various organs from the growing and fully grown bird. Attention was called to the fact that those organs and tissues which yielded growth-promoting extracts were just those which have been shown by Warburg and his school (Warburg, 1930) to possess considerable powers of glycolysis. The parallelism is illustrated in Fig. 1. In the upper series are plotted the mean mitotic indices for the fibroblast cultures during the period from the tenth to the twentieth hour after the addition of the tissue extracts, at which time the effects produced by such extracts have been shown to be most comparable. In the lower series, the anaerobic glycolytic activities, as measured by lactic acid production, of the corresponding tissues are plotted. Comparison of these two sets of figures at once suggests that the organ extracts may exert their effects by influencing the carbohydrate metabolism of the tissues to which they are applied. The only apparent exception is the thyroid, and the effects of extracts of that organ on the growth of cultures were very variable and probably other factors were involved.