Pathology and ultrastructural characteristics of a hypomelanotic variant of transplantable hamster melanoma with elevated tyrosinase activity.

摘要: Abstract A spontaneous, hypomelanotic variant (MI) of the highly melanotic transplantable hamster melanoma Bomirski (Ma) is subject this report. Tyrosinase activity 2–3 times higher, but melanin content significantly lower than in parental Ma melanoma. Acid phosphatase similar both, β-glucuronidase and aryl-sulfatase are higher variant. Transplanted MI melanomas grow more slowly tumor, metastasize with incidence localization. Hypomelanotic cells, even those grossly nonnecrotic parts transplants, show signs low viability like swelling cytoplasm or cellular condensation, disintegration. Autophagic vacuoles numerous. They appear to be formed by enclosure a portion cisternae smooth endoplasmic reticulum trans-Golgi network. These limiting contain tyrosinase as evidenced deposition electron dense reaction product on incubation tyrosine DOPA. Other sites ultrastructural melanosomes smooth-surfaced vesicles We postulate that cell viability, associated autophagosome formation, cause for growth retardation variant, these tyrosinase-rich cells due sequestration substantial newly synthesized enzyme into autophagic before it has chance being incorporated melanosomes.