EFFECT OF BENZENE ON FETAL GROWTH WITH SPECIAL REFERENCE TO THE DIFFERENT STAGES OF DEVELOPMENT IN MICE

Abstract

Female mice with vaginal plugs (1st day of gestation) were divided into two groups. In the first group (Group I), benzene was injected on 8th and 9th day and in the second group (Group II) on 12th and 13th day of gestation once a day. Each of the two groups was composed of three subgroups. In the first subgroup, mice were injected with 2 ml/kg benzene and in the second subgroup with 4 ml/kg benzene subcutaneously. The third subgroup was used for control. On the 19th day of gestation, mice were sacrificed and their uteri were examined for resorp-tion and implantation sites. Fetuses were weighed and external examination of malformation was performed. Skeletal preparations were also examined. Furthermore, blood samples were obtained from the tail before and after injection of benzene. In this experiment, a significant increase of congenital anomalies could not be observed. However, the dose-response relationship between benzene injected to pregnant mice and the weight gain of fetal body was inversely demonstrated in the case of Group I. In Group II, only the subgroup injected with 4 ml/kg benzene showed a significant decrease of weight gain of fetal body and placenta, and retardation of progress in ossification of the extremities. On the other hand, the unmistakable decrease in white cell counts and hemoglobin content of mother mice was consistent with the decrease of the weight gain of fetal body as a phenomenon among subgroups injected with benzene in both Group I and II.