Table 1.

Fluorescent microscopy detects the progression of apoptosis in HL-60 cells following induction with VP-16^a

	Control (%)			Induced (%)
Time
(h)	Hoeschtb	PIc	PI/Hoeschtd	Hoeschtb	PIc	PI/Hoeschtd
0	3.5	3.5	100	5.6	5.6	100
2	2.8	2.8	100	2.5	2.5	100
4	5.0	5.0	100	6.9	4.6	67
6	3.3	2.0	60	22.5	5.1	22
8	2.9	2.2	75	31.5	15.0	48
10	9.4	8.1	86	33.0	21.1	65

^aAliquots of HL-60 cells harvested at the indicated time points were stained with a combination of the nuclear stain Hoescht 33342 and the vital stain propidium iodide (PI). Total number of cells (n > 100) was determined by fluorescence microscopy using Hoescht 33342.

^bCells displaying condensed chromatin that stain with Hoescht as a percentage of the total number of cells counted.

^cCells displaying condensed chromatin that stain with both Hoescht and PI as a percentage of the total number of cells counted.

^dCells displaying condensed chromatin that stain with PI as a percentage of the cells displaying condensed chromatin that stain with Hoescht 33342.