Lung growth and maturation in experimental oligohydramnios in the rat.

Abstract

On day 16 of gestation the amniotic sacs of either the right or left uterine horns of timed-pregnant Sprague-Dawley rats were punctured with a 20-gauge needle. The fetuses of the opposite horn served as controls. On day 21 of gestation (1 day prior to natural delivery), the fetuses were delivered by Cesarean section. Amniotic sac puncture resulted in a significant loss of amniotic fluid. Fetal growth retardation occurred. Lung growth was specifically retarded, as indicated by significantly reduced lung weight to body weight ratios and lung volume to body weight ratios following amniotic sac puncture. There appeared to be no effect on the structural units of the lung, since no differences between control and experimental fetal lungs were observed in terms of deoxyribonucleic acid, nonconnective tissue protein, total phospholipid, and disaturated phosphatidylcholine per gm dry lung weight. The ratios of disaturated phosphatidylcholine to total phospholipid and nonconnective tissue protein to deoxyribonucleic acid were unchanged. The volume proportions of saccular air, saccular wall, bronchial and bronchiolar air and nonparenchyma, peripheral airspace size, and surface-to-volume ratio were also unchanged. Thus loss of amniotic fluid significantly affected lung growth, more than it affected overall body growth, without having an effect on lung maturation.