Mouse epidermal and skin extracts tested for cytostatic activity ("chalones"). Effects on organ and cell cultures.

Crude and fractionated epidermal extracts have been shown to decrease the growth and viability of epidermal cells (mouse ear organ cultures) as well as of murine mastocytoma cells, fibroblasts (L cells) and kidney cells (primary cultures). This cytotoxicity has been demonstrated to be due to the extracts and not to parasitic toxins. Furthermore, extracts prepared from dermis, mammary glands, and liver were likewise cytotoxic. These results do not confirm the presence of tissue-specific growth inhibitors (chalones) which have been claimed by others to be present in epidermal extracts.