title: Dedifferentiation of a transplantable papillary thyroid carcinoma over a 15-year period.
abstract: Fischer 344 rats on a prolonged low-iodine diet developed thyroid nodules which were transplanted subcutaneously into 33 thyroidectomized rats. One graft took and gave a papillary carcinoma. Serially transplanted syngeneically at 3- to 4-month intervals, it became autonomous in third generation hosts. With electron microscopy examination it was microfollicular in year 8 and anaplastic, with totally unpolarized epithelial cells, in year 15. Basement membrane present in year 1 was no longer visible in specimens of years 8 and 15. Tight and gap junctions still present in year 8 were absent in year 15, although a few desmosomes persisted. From years 8 to 15, free ribosomes and microfilaments became more frequent, whereas the number of mitochondria and the development of the Golgi complex declined.
mesh_terms: D000818:Animals; D002291:Carcinoma, Papillary / Q000473:pathology* / Q000648:ultrastructure; D002454:Cell Differentiation; D003896:Desmosomes / Q000648:ultrastructure; D007365:Intercellular Junctions / Q000648:ultrastructure; D008854:Microscopy, Electron; D009368:Neoplasm Transplantation; D051381:Rats; D011916:Rats, Inbred F344; D013964:Thyroid Neoplasms / Q000473:pathology* / Q000648:ultrastructure; D013965:Thyroidectomy; D013997:Time Factors