Differences in mitotic cycle in various tissues of Vicia faba roots as revealed by 5-amino uracil synchronization of cell division

Longitudinal sections of lateral roots of Vicia faba, pre-treated with 5-amino uracil, were analyzed for the appearance of areas of synchronized cell division. The first evidence of a recovery from the inhibitory effect of amino uracil is seen in the pre-cortical tissues proximal to the root initials. This zone of cell division moves distally toward the apex. Cell division begins in the central cylinder later than in the cortex and moves distally to the pole, ultimately including all the apex except for a small field of interphase cells in the quiescent center.