Fig. 3.

Difficulties. Cell number and location in a packed cluster cannot be robustly assessed with known methods and even sometimes by human vision. Each row shows 5 consecutive frames of a video example that illustrates the variety of difficulties this assay presented. a a frequent case where one of the cell is out of focus, (b) another frequent case where cells are overlapping, (c) a case showing both overlapping and out of focus cells, (d) a case where a cell enters the field of view just before mitosis, (e) another case showing overlapping cells. Scalebar is 20 μ m