Developmental expression of SP-A and SP-A mRNA in the proximal and distal respiratory epithelium in the human fetus and newborn

摘要: We used immunolocalization and in situ hybridization to determine the distribution of SP-A mRNA lungs human fetuses normal newborn infants. Early second fetal trimester a few immunostained cells were observed tracheal epithelium, often mucosal folds near origin submucosal gland ducts. Non-mucous for as they became differentiated. Expression was similar that trimester. Immunostained also appeared about same time gestation isolated bronchial epithelium glands. seen bronchiolar pre-Type II lining terminal airways at 19-20 weeks gestation. Only liveborn infants did bronchioloalveolar portals mature Type contain or immunostain SP-A. In postnatal infants, luminal material stained Although some alveolar macrophages contained immunoreactive material, never detected. The abundance glands conducting supports importance non-surfactant-associated functions may be related role host defense.