Physiology Which of the following factor is responsible for the pulmonary alveoli to be kept dry under normal circumstances? A Macrophages B Tight junction between endothelium and alveolar surface C Pulmonary surfactant D Negative interstitial pressure 💡 Explanation Which of the following factor is responsible for the pulmonary alveoli to be kept dry under normal circumstances? ✓ Correct Answer: D. Negative interstitial pressure