Radiation effects on tumour cell nuclear diameters. The X-axis shows the numbers of days of treatment. The nuclear diameters were measured in a defined reference area in the centre of the tumour; one to three sections were measured in two to four tumours from each group. Bars that are close together represent results from different sections of the same tumour. The nuclei were measured in different tumours for the untreated group (n = 2), the 1-day-treatment group (n = 2), the 5-day-treatment group (n = 4), the 12-day-treatment group (n = 4), and the group with regrown tumour cells (n = 2).