Aplasia/Hypoplasia of the lungs Congenital alveolar dysplasia 2020-10-12T11:35:45Z Arrest of lung development in the cananicular stage (weeks 18 to 26 of human gestation) resulting in simplified acinar spaces, frequently with abundant intervening mesenchyme and no alveoli. In later arrest growth stages early saccular formations may be seen. May resemble the lobular maldevelopment often seen in alveolar capillary dysplasia/misaligment of the pulmonary veins without vein misalignment or marked hypertensive changes of the pulmonary arteries.