The present examinations has been performed on 69 Holstein Friesian bulls and heifers in the age between 18 and 36 months, to show macroscopic- and microscopic-anatomical dates of the hearts, kidneys and adrenal glands. Age- and sex-dependent questions were discussed. Among the heifers three age related classifications were made. The special interests of the microscopic- anatomical evaluation are the description possibly correlations as a reflection of the renin-angiotensin-aldosteron-system and the atriale natriuretic peptide. The macroscopic- and microscopic-anatomical dates show for the entire sample numerous age- and sex-dependent differences. Between the macroscopic and microscopic-anatomical dates existing in both sexes and in the heifer age group correlative connections. The bulls show in the right atrium-wall a larger nucleus volume, whereas heifers exhibit a significant greater intramyocardial connective tissue. The kidneys show sex-unrelated larger cortical renal corpuscles compared to the juxtamedullary renal corpuscles. The renal corpuscles volume in the cortical and juxtamedullary zone increase with age, the corpuscles density decrease in both zones. The distance of the first ten to the cortex renalis localized corpuscles, will be age related larger. Sex-related differences in the microscopic-anatomical kidney dates are seldom proved. The bulls show larger nuclei-volume of the zona glomerulosa cells, compared to the heifers. Between the microscopic-anatomical dates numerous correlative relations are shown. In the heifer group it was found on the light microscopic level an slight indication to hormonal correlations between the intramyocardial connective tissue and the size of the cortical glomerulus. The correlation coefficient seems to reflect a cause-effect relation between hypertension as an result of the renin-angiotensin-aldosteron-system and the microscopic- anatomical structures.
