Fig 1. Heterogeneity in experimental measurements of spheroid growth.

(A) Microscopy images of tumour spheroids grown from melanoma cell line WM983b from which a subset of measurements in (B) were taken. Spheroids were grown from 5000 cells, harvested, fixed, and imaged after nine days. Cells are transduced with fluorescent cell cycle indicators: colouring indicates cells in gap 1 (purple) and cells in gap 2 (green). In all but one spheroid, a lack of definition in the spheroid centre indicates the presence of a necrotic core. (B) Images are summarised by the radius of a circle with equivalent cross-sectional area as microscopy images. Shown are experimental measurements (blue discs and box plots) and a calibrated logistic model with prediction interval based on additive normal noise. Data from [20].