The impact of external environment on pulmonary development – a morphological evaluation of pulmonary tissue in preterm infants

Preterm birth disrupts the natural progression of pulmonary development, which can trigger functional and morphological consequences that may lead to death or the development of a chronic lung disease. The objective of this research was to evaluate the pulmonary morphological characteristics in 67 preterm neonates who had survived for a minimum of 24 hours. All evaluations were carried out on paraffin-embedded lung tissue, sliced at 5 micrometers, and stained with a standard hematoxylin-eosin stain. From each case, photomicrographs of one square millimeter were assessed, and the quantity of alveoli, the diameter of the alveoli, the thickness of the alveolar septum, and the total thickness of the arteriolar and venular walls were measured. The research findings revealed that prolonged oxygen therapy has an impact on the density of alveoli per square millimeter in premature infants, regardless of their gestational age at birth. Additionally, neonates with lobar lung abnormalities exhibit a reduced number of alveoli per square millimeter. Moreover, preterm neonates delivered at extreme gestational ages demonstrated a notably reduced alveolar diameter compared to those born at more advanced gestational ages, and infants who developed bronchopulmonary dysplasia may exhibit increased alveolar septal thickness compared to other newborns.