[Structure of the endothelium of the thoracic and abdominal aorta of intact rats studied by various methods of preparation and handling of the specimens].

By means of scanning and transmissive electron microscopy structural peculiarities of endothelium of the thoracic and abdominal parts of the intact rat aorta have been studied at various regimens of preparation and making specimens . The greatest changes endotheliocytes (EC) undergo at using immersion fixation after dissection of the aortal segments. These changes are less pronounced at immersion fixation in situ. A decreased perfusion pressure results in appearance of intimal folds and microfolds on the surface of EC. Increasing time for washing more than 1 min results in appearance of inflations and craters on the surfice of EC. For analysis by means of transmissive electron microscopy it is not necessary to remove blood completely out of the vascular bed. The most essential factor is to maintain perfusion pressure at the average systolic level in the given area of the vessel. However, to make the analysis by means of scanning electron microscopy this method is not suitable. The most optimal condition for initial stages of preparing vessels for morphological investigation is their washing for 1 min in the medium 199 with addition of heparin (10 units/ml) during no more than 1 min with a subsequent perfusive fixation in 2.5% solution of glutaraldehyde in the medium 199 no less than 5 min under the average arterial pressure in the given area of the vessel.