A computer image analysis was done to investigate the distribution of tenas
cin and collagenous matrix components (collagen types I and III) in the cho
rdae tendineae of the anterior cusp of the left ventricular papillary muscl
e, using confocal laser scanning microscopy in both a 20s age group and an
80s-90s age group.
Tenascin and the collagenous matrix components showed marked accumulation i
n the 80s-90s age group with elastic fiber concentration being increased in
the same region as that in the 20s age group. The highest content of inter
surface layer staining with an anti-tenascin antibody and with anti-collage
n type III in the inner layer was found in the 80s-90s age group. These con
tent levels were low in each region in the 20s age group. The distribution
and content of these extracellular matrix changes are related to the change
s in mechanical performance of the cardiac muscle with age.