The progression from in utero to extrauterine viability entails the production of pulmonary surfactant, transformation of the lungs from secretory to respiratory organs, and the maturation of parallel pulmonary and systemic circulations. The pivotal role of surfactant becomes evident during the infant's initial breath. The treatment of infants with RDS has largely been revolutionized by the development of natural, semi-synthetic, and synthetic surfactants. The Life Cycle of Surfactant Surfactant is a biological substance produced by type II secretory cells of the lung. The components of surfactant are synthesized in the endoplasmic reticulum of type II cells and subsequently transported via the golgi apparatus to the lamellar bodies.
Intracellular surfactant is stored within the lamellar bodies.
Upon release of the surfactant from the cell via exocytosis, the surfactant aggregates to form tubular myelin. Type II cells clear surfactant from the pulmonary system largely through reuptake. Phospholipids are recycled for secretion or degraded to provide the basic constituents for the formation of new phospholipids. Figure 3 illustrates the synthesis and degradation of surfactant. DPPC is the major surface-active component in surfactant.