[Spontaneous tumors in rats from the Rappolovo Breeding Nursery of the Academy of Medical Sciences of the USSR].

The authors report the data on the incidence of neoplasms in rats of the "Rappolovo" nursery breeding (USSR Acad. Med. Sci.) and their offsprings during 4 sequential generations kept in the vivarium of the N. N. Petrov Research Institute of Oncology of the USSR Ministry of Health. The frequency of spontaneous tumors in 213 male and 230 female rats was 25.8 and 35.7% accordingly. Totally, male animals developed 65 tumors, females--114. over 80% of all neoplasms developed in animals older than 18 months. The frequency of neoplasms of separate localizations in males and females was as follows: the hypophysis--7.0 and 12.6% correspondingly; the mammary gland--0.5 and 11.7%, the thyroid (thyroidal epithelium) - 1.4 and 3.0% and (light cells) 5.6 and 8.3%; the adrenal cortex--0.5 and 1.3%; the hematopoietic system --7.0 and 5.6%; parasitic sarcomas of the abdominal cavity --5.6 and 3.0%; the skin --0.4 and 0.4%; soft tissues --0.9 and 0%; the liver--0.4 and 0.4%; the kidneys --0.4 and 0.4%. Moreover, one male showed seminal vesicle tumor, and females-solitary neoplasms of the pancreas and salivary gland, the dura mater, the ovary and uterus. Significant differences were revealed in the frequency of spontaneous neoplasms in separate rat generations.