A reappraisal of the stathmokinetic technique. I. An experimental study of a murine plasmacytoma with special reference to metaphase degeneration.

An "in vivo" study of metaphase degeneration in the murine plasmacytoma (MPC 11) over 8.5 h after mitotic arrest with vincristine sulphate and labelling with 3H-TdR is described. The main points to emerge were that: (1) Metaphase degeneration becomes apparent from the decline in the unlabelled metaphase collection function after 3 to 4 h; (2) the decline is such that by 8.5 h approximately 25% of the metaphases which were present in the tissue at 3 h are no longer identifiable entities; (3) No circadian variation in the mitotic index was found; (4) 3H-TdR may have a retarding effect on the entry of labelled cells into mitosis.