Selective Staining of Pulmonary Type II Alveolar Cell Lamellar Bodies in “I-Micron” Plastic Sections

Abstract

Schlipköter in 1954 described a concentric lamellated osmiophilic body contained within the cytoplasm of certain pulmonary alveolar epithelial cells. The occurrence of these bodies and microvilli on the free cell border is the ultrastructural trademark of the type II alveolar epithelial cell. Numerous reports have been made concerning the histogenesis of this cell type and the composition and function of its lamellated inclusions. Though the significance of these bodies remains undetermined, their faithful occurrence facilitates the identification of the type II cell in fine structure studies.In paraffin sections of lung tissue, vacuoles are found in those cytoplasmic areas of the type II cell which are normally occupied by the lamellar inclusions. Presumably a chemical extraction has occurred during the embedding procedure. Thus, the identification of the type II cell in these sections is based mainly upon its shape and location. When 1-2 micron-thick sections of plastic-embedded lung tissue are stained with methylene blue and azure II, then counterstained with basic fuchsin according to the method of Mackay and Mead, the lamellar bodies of the type II cell show an affinity for the basic fuchsin.