Light and electron microscopic findings on experimental melanomas after hyperthermia at 50 degrees C.
The effect of hyperthermia, 50 degrees C applied for 5 min, on the development of lesions in hamster Greene melanomas was investigated. Hyperthermia was induced by a laser that produced radiation at 780-880 nm. Hamster melanomas were also examined after arrest of the blood circulation to differentiate between heat-induced lesions and those caused by ischaemia due to vascular occlusion. Tumours were removed 5 and 30 min and 1, 3, 6 and 24 h after thermotherapy. The cytotoxic effects of heat and ischaemia were examined by light and electron microscopy. Hyperchromatic nuclear staining, the first hyperthermia-induced lesion, was detected in the superficial layers of the tumour 5 min after heat treatment. The lesions had progressed to severe pyknosis and extended into deeper layers of the tumour 1 h after hyperthermia. At 24 h necrosis was observed at a depth of 6 mm. The hyperthermia-induced lesions differed markedly from the ischaemia-induced lesions, in that the latter showed early mitochondrial damage but nuclear pyknosis did not become manifest until 3 h after arrest of the blood circulation.
Journée-de Korver
J G
JG
Department of Ophthalmology, Leiden University Medical Centre, The Netherlands.
Oosterhuis
J A
JA
Vrensen
G F
GF
D000818:Animals; D002467:Cell Nucleus / Q000648:ultrastructure; D002843:Chromatin / Q000648:ultrastructure; D006224:Cricetinae; D006979:Hyperthermia, Induced; D007511:Ischemia / Q000473:pathology; D008297:Male; D008546:Melanoma, Experimental / Q000098:blood supply / Q000628:therapy / Q000648:ultrastructure*; D008647:Mesocricetus; D008854:Microscopy, Electron; D008928:Mitochondria / Q000648:ultrastructure; D009336:Necrosis; D012878:Skin Neoplasms / Q000098:blood supply / Q000628:therapy / Q000648:ultrastructure*; D013997:Time Factors
D002843:Chromatin