Collagen in Normal Mouse Glomeruli

Abstract

THE mesangial region of the normal renal glomerulus has been the subject of controversy for many years and is the site of collagen production in some diseases^1,2. Although there have been many investigations in a variety of animals, we are aware of only one published account which has described collagen fibrils in the normal glomerulus. These were described in the rat². During investigations of experimental renal amyloidosis in the mouse we had cause to examine the glomeruli of normal animals. Careful search of the mesangial regions revealed the presence of typically striated collagen fibrils with periodicity 500–600 Å and showing intraperiod striations. Fig. 1 shows parts of two mesangial cells (the arrows point to collagen fibrils). Fig. 2 is a higher power electron micrograph of the area indicated between the arrows in Fig. 1. The tissue was fixed in buffered osmium tetroxide solution, embedded in ‘Araldite’, and after sectioning stained for 1 h with 2 per cent phosphotungstic acid dissolved in absolute alcohol.