Vascular pattern in the chorioallantoic membrane (CAM) after laser/photosensitive compound treatment. II. Microscopic findings.

The formation of clusters of densely packed primitive erythrocytes in growing capillaries and primitive vascular stems of chicken chorioallantoic membrane (CAM) after laser/meso-tetra(sulfonatophenyl)porphine dodecahydrate tetra-sodium salt (TPPS4) was studied. The soluble TPPS4 penetrates easily through the CAM epithelium and stroma into vascular lumina and accumulates predominantly in red blood cells. Accumulation of TPPS4 in immature erythrocytes persisted in higher levels in comparison with the primitive endothelium after day 2 of incubation. Laser/TPPS4-treated primitive red blood cells became sticking on the inner surfaces of tiny CAM capillaries and numerous "erythrocytic plugs" were quickly formed in irradiated CAM areas. Small erythrocytic clusters were also found after prolonged laser irradiation especially in superficial capillary network in CAM. Slight red blood cell disintegration, followed by blood leakages through vascular ruptures, was found after day 2 of further reincubation.