A-E: Spouting of new vessels in primary ossification centres of the growth plate. CD34+ (green) endothelial cells formed cascades that had not been stabilized by α-SMA bearing sub-endothelial smooth muscle cells (blue) in immature vessel formations. F-J: Vasculature in the surrounding articular soft tissue showed continuous lining of CD34+ (green) endothelial cells partly sharing (yellow) endothelial CD31+ (red) presence in already α-SMA bearing sub- endothelial smooth muscle cells (blue) stabilized mature vessels. K-L: Mature vessels with a lumen and CD34+ (green) and CD31+ (red) endothelial cells as well as α-SMA bearing smooth muscle cells (blue) A-L were displayed in confocal Laser Scanning Microscopy (630x magnification), all cellular nuclei were counterstained with DAPI (white). To enable comparison across the panel of CD34, CD31 and α-SMA, parameters for data acquisition were kept constant.