ISOLATED COLLAGEN-IV RETAINS THE POTENTIAL TO FORM AN 18-NM SIDED POLYGONAL MESHWORK OF THE LAMINA DENSA

Polygonal meshworks were revealed in the aggregates reconstituted from isolated collagen IV as well as in the lamina densa of mouse pancreas by the quick-freezing and deep-etching technique. Collagen IV solubil ized with acetic acid from the bovine lens capsules and that isolated from the pepsin-solubilized fraction of human placenta reconstituted p olygonal meshworks, which were dimensionally similar to the meshwork s een in the lamina densa of mouse pancreas. The average lengths between branching points in the lamina densa, and in the meshworks of collage n IV derived from the bovine lens capsules and from the human placenta were 20.1 +/- 7.7 nm (mode = 18 nm), 21.6 +/- 11.3 nm (mode = 14 nm), and 21.6 +/- 9.0 nm (mode = 18 nm), respectively. These observations suggest that collagen IV can, in the absence of other macromolecules i ncluding laminins, comprise a skeletal meshwork similar in dimensions to that of the lamina densa.