Cell cycle S-phase labeling by nucleoside analog incorporation with EdU (green) showed a higher rate of cell proliferation in the capping mesenchyme at P2 than at P1. At P2 the cap surrounding ureteric bud branch tips (blue - E-cadherin) contained many more cells which incorporated the label. The optical sections at P1 and P2 were obtained at the same level relative to the branch tip of the ureteric bud, just superficial to the central lumen in the branch tips of the ureteric bud. Bar = 50 microns.
Brunskill et al. BMC Developmental Biology 2011 11:15 doi:10.1186/1471-213X-11-15