HISTOPHYSIOLOGY OF THE ACINUS. LUNG REGENERATION AND TRANSPLANTATION

This article provides a detailed examination of the histological structure, cellular composition, and histophysiological characteristics of the acinus—the primary structural and functional unit of the lung. It analyzes the roles of alveolar epithelium (type I and type II alveolar epithelial cells), capillary endothelium, the interstitium, and alveolar macrophages in processes such as gas exchange, surfactant synthesis, fluid balance, and local defense mechanisms. Furthermore, the article explores the physiological renewal of lung tissue and the mechanisms of regeneration following injury—involving type II alveolar epithelial cells, basal cells, bronchoalveolar stem cells, and regenerative niches—as well as the consequences of impaired regeneration (such as fibrosis and emphysema). It also addresses the histological and immunological foundations of lung transplantation, potential complications, and contemporary developments in the field, including *ex vivo* perfusion, bioengineering, organoids, and xenotransplantation.