Peculiarities of the Connection between Mesangial and Glomerular Endothelial Cells in the Domestic-swine Kidney

Summary It is established that cytoplasm fragments of the endothelial cells, located between the mesangial angles, abruptly extend their size, and borders between them are difficult to discern. They possess single microvillia on their lumenal surface, some of which are highly corrugated, branched and fenestrated. In those parts, the mesangial‐cell excrescences are tightly enveloped by the endothelium, some of them contacting directly with the capillary lumen. On the border between the mesangium and the juxtamesangial part of the endothelium, two types of vesicles, directed towards the capillary lumen, are observed. The first type of vesicle is bigger and has a deeply narrowing section, which is directed towards the mesangium. The second type of vesicle is enveloped by a two‐layer membrane, which, in almost all cases, is connected to the endothelium. Peculiarities in the localization of the podocyte excrescences are also detected, which gives reason to presume that the epithelial cells play an important part in the biomechanics of the renal glomerulus.