The high resolution ultrastructure of the periodicity and architecture of lipid-retained and extracted lung multilamellar body laminations

Abstract

High resolution electron microscopy was utilized to study the periodicity and architecture of rat and monkey, lung multilamellar bodies. In lipid retention embedments and polar dehydrants, the lamellar width (LW) was defined as a lipid bilayer. The osmiophilic band that contained two layers of phospholipid heads (PH) of adjacent lipid bilayers in immediate opposition and the translucent band or fatty ah = 35-38 a, fa = 31 a; hydroxyethyl methacrylate glutaraldehyde and urea embedment or fatty acid tail layer(FA) were also measured: glutaraldehyde and urea embedment, LW=66 A, PH=35-38 A, FA=37 A; Epon 812 resin polar dehydrant, LW=66 A, PH=35-38 A, FA=31 A; hydroxypropyl methacrylate polar dehydrant, semihomogeneous matrix without laminations. There was no interlamellar space, so that lamellar width was also the periodicity. In slightly extracted material the PH layer was usually the site of extraction. These results were considered in light of the previously reported measurements of extracted, lipid retained and frozen etched material. In vivo lamellae are probably 66 A wide, composed of 35-38 A PH and 31 A FA layers and do not exhibit an interlamellar space; Lamellae were observed to fracture at the FA layer at bends, to bifurcate and to anastamose.