Penetration of Benzpyrene through the Intact Skin of New-Born Mice

Abstract

WHEN the skin of the mouse is painted with a benzene or an acetone solution of a carcinogenic hydrocarbon, it is found afterwards that a part of the carcinogen remains in the keratinized layer of the epidermis, while some of the carcinogen (fluorescent material) immediately enters the pilo-sebaceous apparatus and is found dissolved in the lipid droplets within the gland cells. Several authors have suggested that the pilo-sebaceous apparatus plays an important part in the genesis of skin cancer by providing channels through which the carcinogen may penetrate the epidermis¹. It was thought that a study of carcinogenic action on new-born mice^2,3,4 would throw light on this problem, for it has been observed that newborn mice (2–10 hr. after birth) are refractory to a single application of methylcholanthrene. The absence of sebaceous glands, the lack of a way of entering via the hair follicles and also the thicker epidermis of new-born mice, confirmed by histological examination, would explain ineffectiveness of methylcholanthrene for tumour formation. The literature does not seem to contain any convincing evidence that the carcinogen is absorbed by the epidermal epidermis without mediation of the follicular pathways.