Confocal Imaging of an Acinus

Abstract

The fundamental ventilatory unit in the design of the respiratory part of lung is the acinus. This term was first mentioned by Rindfleisch in 1878 (see Miller 1937). The term has been well fixed in the clinical literature since 1935 (Aschoff 1935). Various slightly different definitions about the proximal termination of this unit exist. It is, however, widely believed that all structures in the acinus participate, to a lesser or higher degree, in the gas exchange, whilst all structures proximal to the acinus are of air conducting nature only. Differences in this definition mainly address the gradual, transitional alveolarization in the bronchioles which are different in various species and the corresponding intra-individual developmental schemes (Valerius 1992).