Tumor-related reconstitutive vascularization. An ultrastructural study.
The nonmetastatic derivative of the pancreatic adenocarcinoma BSp73 of the BDX rat, BSp73 AS (AS), was used to generate solid lung colonies by the intravenous route. Vascularization could be seen within the tumor nodules and in the surrounding, highly disorganized lung tissue. We concentrate here on the formation of capillaries in the surroundings of pulmonary AS foci. The formation of capillary lumina can be described as follows: first, a lumen is formed between an endothelial cell (EC) and its basal lamina (BL) by partial detachment of the EC. The denuded BL is then re-coated by EC protrusions until the lumen is newly lined. A similar process is observed at the abluminal surface of ECs of vessels just beneath the surface of alveolar lumina. In this case, ECs detach from their BL and generate stilts, thus bulging adluminally. The naked BL is then recoated by EC protrusions. Finally, small closed lumina are formed by the ECs. These events occurring during vascularization are interpreted as morphogenetic reactions of normal cells to tumor-derived stimuli. Vascularization of this kind takes place within peritumoral, disturbed alveolar tissue and appears to be aimed at reconstituting a normal alveolar histology in order to overcome the destruction caused by the tumor. In this study we show the highly complex reactions between normal and neoplastic tissue.
D000230:Adenocarcinoma / Q000098:blood supply; D000818:Animals; D002460:Cell Line; D005260:Female; D008168:Lung / Q000098:blood supply; D008854:Microscopy, Electron; D009374:Neoplasms, Experimental / Q000098:blood supply*; D009389:Neovascularization, Pathologic / Q000473:pathology*; D010190:Pancreatic Neoplasms / Q000098:blood supply; D051381:Rats