Files in this Data Supplement:

• Supplemental Methods - (Word) (32 KB)
• Figure - (Power Point) (2.4 MB) Sections of tissue taken from the sinoatrial node taken from near to the leading site of spontaneous pacemaker activity. Section A is taken from an 18 month guinea pig and section B from a 38 month animal. The tissue has been stained with aniline blue, which stains collagen blue, and fuschin red, which stains the myocytes red/magenta. In both cases collagen is chiefly located in the epicardial region of the tissue and myocytes are present continuously across the nodal structure. No apparent changes in collagen distribution or morphology of the constituent myocytes of the node were observed between the adult and elderly animals.