Spontaneous Malformations in Laboratory Animals: Frequency of External, Internal and Skeletal Malformations in Rats, Rabbits and Mice *

The investigation of the frequency of spontaneous malformation in laboratory animals was done by Professors Yoshiro Kameyama, Takashi Tanimura and Mineo Yasuda in the editorial section of “Congenital Anomalies” in 1980, and the data were published in “Congenital Anomalies” Vol. 20, No. 1 , 1980. But it is usual that the background data become old as the time passes, and more and newer data are required. Under this circumstance, Prof. Takashi Tanimura as the President of the 25th Annual Meeting of the Japanese Teratology Society requested Non-Clinical Evaluation Subcommittee (Chairman. Kazunaga Fukawa) of Japan Pharmaceutical Manufacturers Association (JPMA) to collect and edit the background data and then publish them in “Congenital Anomalies” as one of the commemorative activities of the 25th anniversary of the Japanese Teratology Society. The Non-Clinical Evaluation Subcommittee has organized a team for investigation and has asked the investigation to the pharmaceutical companies belonging t o JPMA and contract laboratories. Editing of the data has been conducted under the guidance by the editorial section of “Congenital Anomalies”. This report describes the results o f the investigation on the occurrence of anomalies in external and internal organs and skeletal system and variations in morphological examination in the control animals (untreated, vehicle control) of the reproduction studies which were conducted between 1980 and 1985 concerning the laboratory animals now used in the reproduction studies in Japan. The data have been collected on three species of animals (mouse, rat and rabbit) by sending an investigation form in June 1985 t o 52 research institutes which agreed with the investigation. In editing, the data collected have been arranged by the species, strain and origin. If the data on