Confocal 3D imaging of beta-glucuronidase (GUS) histochemical staining in Arabidopsis thaliana root tips. The blue reaction product resulting from the indigogenic histochemical reaction exhibits fluorescence near 700 nm and is thus amendable to 3D confocal imaging. The GUS staining is predominantly present in the root cap and rhizodermis. Olympus FV1000 confocal microscope, 60x/1.2 water immersion objective, excitation by 633nm laser. Sample courtesy of Sonia Iriyogen, W. Versaw lab (Biology). Image acquired by Stan Vitha.