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Sixty European wild boars (Sus scrofa) of various ages and both sexes underwent post mortem examination with special regards to the heart muscle. The examined boars were divided into groups regarding the estimated ages. With the aim to find sex-specific differences, some groups were further divided into male and female. Only group 2 and 3 had sufficient numbers to be able to demonstrate results graphically.There was an increase in body weight with advancing age. In addition the absolute heart weight increased with age. If however the weight of the heart was taken as a function of the age, there was a decrease in the allometric relation. The relative heart weight was 1,31% in average in group 1 (boars under 6 month of age) and reduced to 0,58% in group 4 (boars over three years of age).Several parameters were evaluated histological on cross-sections of cardiac muscle (measurements and evaluations were supported by electronic light microscope and computer systems). Particular attention was paid to size and number of capillaries, myocytes and other tissue. The cell nuclei were also examined.Older animals showed an increased diameter of capillary vessels in both ventricular walls and a decreased total number of capillaries per p M2. In effect, the percentage unit area comprising capillaries remaining virtually constant. The reason, the capillary vessels, showed an absolute decrease in number when taken as a function of the cardiac surface area. This was due to an increased volume of the myocytes. The average area of the cross-section of one myocyte virtually doubled when comparing group 4 with group 1. Therefore older animals had an increased intercapillary distance.New capillary vessels are developed with increasing age. This was demonstrated as an increase in the capillary vessel: myocytes-q uoti ent in both ventricular walls.There was an increased hyperplasia of myocytes of the left ventricle wall relative to those in the right ventricle; this was assumed to e a result of the increased load onthe left ventricle compared to the right ventricle. With age the plasma: nucleus ratio of" the myocytes increased. In fact the cross-section al area of the nucleus did not increase in linear relationship o that of the myocyte, although it did show an increase in size with age.Small changes in the cross-sectional areas of non-myocytes were noted between the groups: The total number of non-myocytes nuclei per area unit reduced slightly within the higher age group. This process might be explained by the higher demand for space by expanding myocytes. The non-myocytes nuclei group was from various cells. An important part of this group were capillary endothelial cells.In summary if comparing the wild boar with other species, it is observed that the heart is well supplied with capillaries, which lead to good oxygen supply to the musculature.