Pulmonary acinar development in diaphragmatic hernia. Pulmonary acinar development was assessed in 17 autopsy cases of pulmonary hypoplasia associated with diaphragmatic hernia. Morphologic examination was conducted by light and electron microscopy, and morphometric study was achieved by radial alveolar count and biochemical quantitation of surfactant phospholipid. In most cases of unilateral diaphragmatic hernia, the ipsilateral lung was underdeveloped morphologically and biochemically compared with the contralateral lung. However, both ipsilateral and contralateral lungs were well developed in some cases of unilateral diaphragmatic hernia. Thus, acinar development of hypoplastic lung in diaphragmatic hernia is varied. The influence of other conditions, such as oligohydramnios, polyhydramnios, and other anomalies that may influence retention of lung fluid or fetal respiratory movement, should be considered to assess the acinar development of hypoplastic lung in diaphragmatic hernia. 