[Experimental and theoretical studies on the in-vivo production of a partially synchronous proliferating cell population with vincristine].

The problem of whether vincristine can be used to synchronize partially cells in vivo was investigated. After injection of 0,0045 mug vincristine/g body-weight into mice practically all L1210-ascites tumour cells entering mitosis were arrested in metaphase up to the fourth hour. However, no second peak of the mitotic index was observed within 48 hours. Calculation of the theoretical mitotic index to be expected under the present experimental conditions also shows no second peak. The reason for this lack of synchrony is the long releasing time of the arrested cells.