The investigation in vivo of the tissue specificity of pig skin fractions.

Using an established assay system, a whole aqueous extract of pigskin and the fractions derived from it by ultrafiltration were investigated for their ability to inhibit proliferation in epidermal basal cells of mouse pinna skin in vitro. The fraction between 30KD and 50KD was found to inhibit both mitosis and DNA synthesis specifically in epidermal cells. Furthermore, a dose dependent relationship was found between the degree of inhibition of DNA synthesis and the amount of 30-50KD fraction given. The results are discussed in relation to the cytospecific, tissue and organ specific activity of the fractions arising from the assay methods used; furthermore, the implication of interpreting the extent of specificity in this manner is discussed in relation to the definition of the term 'chalone'.