Age-related alterations of proteoglycan in mouse tracheal cartilage matrix: an electron histochemical analysis with the cationic dye of polyethyleneimine.

Age-related alterations of the proteoglycans (PGs) contents and size were observed in the tracheal cartilage matrix of ddY mice at various ages with the cationic dye of polyethyleneimine (PEI). In young animals (aged 1 day to 1 month after birth), the PGs content and size increased, resulting in the formation of the territorial matrix (TM) and the decrease of the space between the PEI aggregates and the collagen fibers. In 1 month old mice, the TM could be distinguished from the interterritorial matrix (ITM). In adult mice (from 2 to 6 months), the PGs content and size kept stable, but the rearrangement of the PGs and collagen fibers was observed. From 6 months of age on, the decrease of PGs content and size occurred mainly in the ITM. The developing stopping sign was recognized in 1 month and the senile sign from 6 months in the ddY mice as for the complete formation of the TM in 1 month and the decrease of the PGs content and size from 6 months. These results demonstrated the age-related alteration of PGs in the ultrastructural level first and could contribute to the aging study of the tracheal cartilage.