A newborn male is tachypneic and hypoxemic after birth. The most likely cause is reduced surfactant production due to decreased lamellar bodies in type II pneumocytes. Which structural change explains this condition?

• A. Increased lamellar bodies
• B. Normal lamellar bodies
• C. Decreased lamellar bodies
• D. Absent lamellar bodies

Answer: (C)

Surfactant is stored and packaged in lamellar bodies inside type II pneumocytes. These organelles release surfactant into the alveolar lining, where it reduces surface tension and prevents alveolar collapse, keeping lungs compliant after birth. When the number of lamellar bodies is reduced, less surfactant is produced and secreted, leading to alveolar instability, atelectasis, and impaired gas exchange. This produces tachypnea and hypoxemia in a newborn, matching the presentation. Hence, a decrease in lamellar bodies best explains the deficiency. Increased or normal lamellar bodies wouldn’t account for reduced surfactant, and absent lamellar bodies would imply a more extreme disruption not typically seen in this scenario.