[A quantitative analysis of the regional organizational characteristics of the aortic endotheliocyte layer in normotensive and spontaneously hypertensive rats].

Using scanning electron microscopy and semiautomatic image analyser, regularities and quantitative changes were studied in endotheliocytes in three regions of thoracic aorta during ageing of normal and spontaneously hypertensive rats of the Kyoto-Wistar line. The data of morphometric analysis and the results of simulating endothelial cell monolayer changes, by means of construction of polyrow mosaics, suggest that the number of small endotheliocytes of normotensive rats in all aorta regions is lowered in the period from 2 to 10 months to increase then from 10 to 16 months. The endothelial cell monolayer changes occur as follows: the small endotheliocytes appear and then disappear, keeping their random distribution in the endothelial layer. Within the same period, in spontaneously hypertensive rats, the behavior of the endothelial layer in the region of intercostal arteria ostia and on the dorsal surface is similar to that in normal rats, being presumably associated with age changes. In hypertensive rats, on the ventral surface of the aorta, a relative number of small cells increases at the expense of small cell foci formation. Thus, the provided evidence points to a heterogeneity of responses of endothelial layers in different regions of the aorta on the constant elevation of pressure.