ADVANTAGES OF SIRIUS-RED STAINING FOR QUANTITATIVE MORPHOMETRIC COLLAGEN MEASUREMENTS IN LUNGS

Sirius Red staining is presented as a method for collagen determinatio n, enabling quantitative morphometric measurements to be performed in locally defined tissue areas. The advantage of this method is especial ly shown for alveolar lung tissue. By excluding the bronchial areas in the tissue sections, the differences in the degree of fibrosis proved to be more discrete after different loads of quartz dust than by any other method. The difference of 12 mu g collagen measured colorimetric ally represented a 1.2-fold increase. The collagen measured in the alv eolar tissue by the morphometric method rose from 9.8 to 28.6%. This i s a 2.9-fold increase, underlining the vast improvement in sensitivity . Thus, this method is specifically suitable for the evaluation of ver y small fibrotic lesions. The quartz doses given are particularly low compared to most other investigations. Histologic lung and lymph node sections from female Wistar rats injected intratracheally with differi ng quantities of quartz dust (0.03, 0.1, 0.5, 1.75 mg) were stained wi th Sirius Red, and the collagen fibers measured with a quantitative im age analysis. The results for lymph nodes using different methods (wet weight determination, quantitative measurement of quartz, typical are as, colorimetric and morphometric collagen determination) showed a hig h correlation at the different doses. This showed that the morphometri c method is suitable for the quantitative measurement of collagen. Cor responding results were also found in the comparative lung tissue meas urements (colorimetric and morphometric collagen determination). Howev er, the morphometric method has the decisive advantage that measuremen ts can be restricted to defined tissue areas and do not destroy the se ction.