Ultrastructural study on endothelial cells in splenic autotransplantation

The splenic tissue of the rat was autotransplanted into the greater omentum to investigate the angiogenic process during splenic regeneration. Chronological observations showed the following two stages. Initially surviving subcapsular sinus endothelial cells migrated to form a preliminary vascular network, which anastomosed with ingrowing omental capillaries to form a circulatory system. In this way, splenic autotransplants would not undergo necrosis and would rapidly form endothelial and reticular cells. At a later stage, the preliminary vascular network differentiated into arteries (arterioles, capillaries), splenic sinuses, and veins. Marked morphologic changes occurred in the endothelial cells, such as vacuole formation, fenestration, and the condensation of intraendothelial microfilaments, resulting in interendothelial slits. These results showed that the formation of a preliminary vascular network caused distinct splenic regeneration and that splenic autotransplantation is a suitable model to study angiogenesis in vivo.