Graphical models of normal vessels and possible abnormal changes thereof (muscular coat hypertrophy or atrophy, and narrowed or intact vascular lumen) have been constructed on the basis of morphometric studies of arteries and arterioles of normal human and white rat heart, liver, brain, lungs, kidneys, stomach, pancreas and small intestine. It is demonstrated that the wall thickness-to-lumen diameter ratio or any similar parameters cannot be used as an unequivocal indicator of vascular change, therefore neither muscular coat hypertrophy, nor narrowed lumen should be regarded as proven in cases of arterial hypertension. The results of the measurement of wall thickness and external as well as inner vascular diameter should be represented as a three-dimensional model for correct assessment of vascular morphogenesis, biomorphosis or pathomorphosis.