[Changes in growth and haematopoietic functions in mice, mothers of which had been injected with benzene during gestation period].

New-born from the mother mouse or rat, which had been injected with benzene during gestation period, has been reported to have a higher susceptibility to benzene or aminopterin than that from a non-treated mother. The present authors' objective is to study whether or not the varied time interval between the day of conception and injection of benzene into mice changes the susceptibility to benzene. Female mice at 6, 9 and 12 days after conception were injected with a dosage of 4ml/kg of benzene, and a control group was not injected. The body weight of the mother mouse just before delivery, percentages of new-born mice vitality at time of birth and after, patterns of occuring death within a week after the birth differed in the 6th day injection group from other groups. The new-born mice at 10 weeks of age were injected 5 times with a dosage of 0.1ml/kg. Consequently, there were marked differences in the leucocyte count, hemoglobin content, body weight and weights of the thymus and the spleen between 9th, 12th day injection groups and the control group.