Composition of intraalveolar surfactant. Relative composition of intraalveolar surfactant in the four groups. Clear differences were noted between healthy and lavaged animals, irrespective whether they were filled with gas or PF5080. While all four different intraalveolar surfactant subtypes (lamellar body-like forms = lbl, tubular myelin = tm, multilamellar vesicles = mv, unilamellar vesicles = uv) were present in healthy animals, there were no measurable amounts of tubular myelin and decreased fractions of unilamellar vesicles in lavaged animals. This was counterbalanced by increased fractions of lamellar body-like forms and multilamellar vesicles in the lavaged groups, indicating a relative increase in freshly secreted surfactant material in the alveoli.