Orientation of adhering junctions between bovine pulmonary fibroblasts

The ultrastructure and orientation of microfilament-attaching junctions between pulmonary fibroblasts (also known as myofibroblasts or contractile interstitial cells) of bovine lung septa were investigated by transmission electron microscopy. Adhering junctions similar to the fascia adherens of the intercalated disc, but of a macular design, link microfilament bundles of adjacent fibroblasts. The bundles of microfilaments joined by junctions were usually aligned perpendicularly to the axis of the alveolar wall. Gap junctions were located in close proximity to the adhering junctions, presumably to co-ordinate the contraction of the cells. The data indicate that fibroblasts are able to form multicellular contractile units within healthy, mature lung parenchyma.