FOR A number of years there has been considerable controversy as to the origin of the fluid normally appearing in fetal lungs. Some believe that its origin is the lung itself,1-7 while others contend that aspiration of amniotic fluid contributes a significant portion.8-10 A study by Jost and Policard2 in which the fetus was decapitated in utero and the trachea ligated showed a dilatation of the alveoli, presumably due to accumulation of fluid in the lung of pulmonary origin; but because of the profound neurological changes associated with such an experiment, the significance of the results remains dubious.
The results of this study performed under near physiologic conditions show that a fluid is produced in the lung, and that normal lung development occurs in the absence of amniotic fluid aspiration. This was done by ligating the trachea of rabbit fetuses several days prior to term and allowing
CARMEL JA, FRIEDMAN F, ADAMS FH. Fetal Tracheal Ligation And Lung Development. Am J Dis Child. 1965;109(5):452–456. doi:10.1001/archpedi.1965.02090020454014