Studies on the Growth of Tissues in Vitro

Abstract

1. Tissue extracts have been made from several organs of growing and adult fowls, and the growth-promoting properties of these extracts have been tested on periosteal fibroblasts growing in vitro. 2. The growth-promoting properties are most pronounced in brain extract and diminish in the sequence: thyroid, thymus, testis, ovary, bone marrow, liver, kidney and muscle extracts. Extracts made from the spleens of adult cocks were found to be far more efficient growth-promoting agents than extracts made from the spleens of young birds. 3. The growth-promoting power of a tissue extract cannot always be correlated with the age of the tissue from which the extract was made, with the rate of growth of that tissue, nor with its nuclear content.