Twenty images from mid-Matrigel H & E sections of all animals in vehicle and propranolol groups were taken randomly at 40× (Zeiss Axiophot II, equipped with AxioCam MRc5 and supplemented with AxioVision Rel. 4.8 software). Luminal structures containing at least one RBC were counted as one vessel; the average from 20 images was expressed as vessels/mm2. Formalin-fixed, paraffin-embedded mid-Matrigel sections were processed and stained with mouse anti-human CD31 (1:40, Dako M0823) or mouse IgG (1:40, Dako X0931) as described18 (link).