A three-dimensional reconstruction of lung parenchyma.

Abstract

The mesoanatomy of the lung is poorly understood despite the numerous methods developed since the classic reconstructions of W. S. Miller (1). Pulmonary macroanatomy has been well demonstrated by dissection and casting-corrosion methods. One can study and define the larger airways in three dimensions following injection-casting of the bronchial tree. The microanatomy of the lung has been the subject' of intensive study and the finest details of alveolar structure have been demonstrated by the electron microscope. An anatomic description of a complete subgross unit of pulmonary parenchyma remains ill-defined and incompletely understood. The study of mesoanatomy fills this hiatus of knowledge between macroand microanatomy. A detailed anatomic description of the alveoli and terminal aborizations of the distal airways is essential to understand the physiologic, clinical, and pathologic significance of this area. The most logical approach to such a study is to model or reconstruct the pulmonary parenchyma. The present writers believe that reconstruction of pulmonary tissue elements (positive reconstruction) is more informative than a reconstruction of the air spaces (negative reconstruction), as it permits the investigator to look into the lung rather than studying it from the outside. Accordingly, a model of a highly magnified small area of the subpleural parenchyma of a normal dog lung has been constructed. It was planned to use this model to redefine the distal airways and alveoli, and to relate the observations to problems of ventilation and perfusion in health and disease.