Autoradiography of Rat Lung before and after Birth

Abstract

THE details of the development of the mammalian lung from late foetal life to maturity are still little known. For several decades many investigators have thought that proliferation in the mammalian alveolar epithelium stops in late foetal life; and that the epithelium then undergoes degeneration and desquamation before birth^1–4. Bertalanffy and Leblond, using a colchicine technique and classical histological methods, showed in 1953 that the alveolar lining cells in adult rat lung are continuously renewed, just as the surface cells of the intestine and skin. Since then, high resolution autoradiography with tritiated thymidine has been applied to the study of cellular proliferation in adult mice and rats. The rates of cellular proliferation of lung tissue have not been studied in the late foetal or neonatal period either with autoradiographic or colchicine techniques. In order to obtain more information on the proliferative properties of lung in the late foetal and early neonatal periods we undertook an in vitro autoradiographic study of the rat lung.