Fig. 1

Generation of Prg4-mRFP1 transgenic mice. a Schematic representation of the Prg4-mRFP1 expression system. The poly-adenylation signal (pA), monomeric red fluorescent protein 1 (mRFP1). b Lateral view of the Achilles tendons and frontal view of a knee joint in wild-type (WT) and Prg4-mRFP1 transgenic (Tg) mice. Upper panels correspond to bright-field images, and lower panels show the red fluorescence from mRFP1. c Histological analysis of the Achilles tendon and knee joint in WT and Tg mice. Semi-serial sections were stained with hematoxylin and eosin (H&E), anti-RFP antibody, and DAPI (for cell nuclei). Immunohistochemistry images are magnified from the squares denoted in each H&E image. Dashed white lines show the border of the tendons and articular surfaces. Scale bars: 200 μm (H&E) and 50 μm (immunohistochemistry). Background red staining of intercellular space and red blood cells by single and double asterisks, respectively