Time of Appearance of Lung Surfactant in the Fœtal Mouse

PATTLE 1 first noted the stability of bubbles formed in the foam expressed from lungs of mature animals and the lack of stability in material from fœtal lungs. Clements 2 emphasized the importance of a bubblestabilizing factor, that is, a surfactant, in the prevention of atelectasis. Lungs from human fœtuses of less than 1,000 gm. usually lack the surfactant characteristic of older fœtuses 3 ; occasionally, lessmature fœtuses possess lung stability 4 .