[The occurrence rate of neonatal anomaly depending on aging of grafted ovaries in C57BL/6J strain mice (author's transl)].

That the birth rate of neonatal anomaly is accelerated by the aging of mothers, number of epidemiological studies have made it clear. Almost no experimental studies, however, have been made in quest of causes for such multi-occurrence of anomalies in the aging of ovaries. The author conducted, in elucidating of basic solution to the subject query, experiments using mice as follows: In order to maintain a constant age of mothers, the different aged ovaries of C57BL/6J-pm strain mice, silver-grey hair, were orthotopical grafted in young (100-200 days in age) castrated female mice, C57BL/6J strain, black hair. Subsequently, such grafted mice were mated with C57BL/6J-pm strain young fixed aged males (100-200 days in age). In such cases, the recipients of ovaries from the silver-grey mice of recessive gene genetically have black hair in color domination, the fact that the birth of silver-grey newborn mice gives full proof of the successful grafting of ovaries. Cannibalism is a common practice in rodents in a case of stillbirth for delivering neonatal anomaly. The author, using such phenomenon, tried to surmise the occurrence rate of malformed neonates. The author also conducted observations on the possible presence of superficial and bone malformation in the newborn mice that were freed from cannibalism. (1) As the age exceeded 401 days in the non-treated C57BL/6J strain mice, whereas the fertility showed a sharp decrease, there was, at the same time, a strong sign of uprising trend in the occurrence rate of superficial and bone malformation. (2) It became clear in the cases of newborn mice from the grafted ovaries that there was a high incidence not only of cannibalism in concert with the aging of ovaries, but also of neonatal anomaly when the age of ovaries exceeded 401 days. This phenomenon bears a close resemblance to that in naturally born mice. The results obtained above have, for the first time, suggested to us that the frequent occurrence of neonatal anomalies related to maternal aging seems likely to be strongly influenced by the ovarian aging, but not by the aging of the other organs in the mother mice.