Abstract
Abstract: Deficient quantity of amniotic fluid causes fetal guinea pig lung hypoplasia. Oligohydramnios that lasts only 5 days in early gestation is sufficient to reduce fetal lung growth significantly. We quantitated lung structural alterations at 50 days gestation (term is 67 days) of fetal guinea pigs whose amniotic fluid was drained on day 45 gestation. The study period spans the late canalicularearly saccular phases of guinea pig lung growth. Compared to littermate controls (n = 4), experimental fetuses (n = 5) have reduced lung:body weight ratio (2.81 ± 0.16 versus 3.21 ± 0.20 × 10−2, p < 0.01), indicating lung hypoplasia. Lung volume is significantly decreased in the experimental fetuses (1.17 ± 0.15 versus 1.34 ± 0.07 ml, p < 0.05). The proportion of lung containing parenchyma (i.e. developing alveoli and alveolar ducts) is reduced following oligohydramnios (0.83 ± 0.04 versus 0.90 ± 0.02, p < 0.025). The hypoplastic lungs contain fewer saccules (fetal “alveoli”) (46 ± 20 versus 69 ± 23 × 106, p < 0.1) and the surface area that would be available for gas exchange is decreased (698 ± 234 versus 974 ± 80 cm2, p < 0.05). Lung volume and volume proportion of parenchyma are reduced in the experimental lung and therefore diminished parenchymal elastic tissue is anticipated. However, the total length of parenchymal elastic tissue in the experimental lungs is decreased to a surprising degree and is little more than half the length in control lungs (504 ± 222 versus 974 ± 70 m, p < 0.0025). Such marked reduction in total length suggests that factors other than smaller lung size have contributed to the decrease of elastic tissue in the experimental group. In fact, elastic tissue length per unit volume is significantly reduced (509 ± 189 versus 809 ± 115 m/cm3, p < 0.025) indicating an absolute decrease in parenchymal elastic tissue in the hypoplastic lungs. These data show that even a brief period of oligohydramnios beginning in the canalicular phase of development significantly reduces and modifies fetal guinea pig lung growth.
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Collins, M., Moessinger, A., Kleinerman, J. et al. Morphometry of Hypoplastic Fetal Guinea Pig Lungs following Amniotic Fluid Leak. Pediatr Res 20, 955–960 (1986). https://doi.org/10.1203/00006450-198610000-00013
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DOI: https://doi.org/10.1203/00006450-198610000-00013