Sequential cytogenetic changes in the evolution of transplanted thyroid tumors to metastatic carcinoma in the Fischer rat.

Inbred Fischer rats fed on an iodine-deficient diet for 16-22 months will develop goiters which will grow into tumors when transplanted subc-utaneously into the flanks of other Fischer rats. We have studied the biologic behavior, histology, and the chromosomes of 1-7 generations of ten lines ot these transplanted thyroid tumors and classified them into three categories: (a) Dependent tumors with a modal number of 42 chromosomes and a "normal" karyotype; follicular and papillary adenocarcinomas;