Fig. 1: Mmrn2 and Clec14a expression at sites of trabecular bone formation.

A Maximum intensity projection images show immunofluorescent staining of Clec14a (orange), Endomucin (Emcn - cyan), Cd31 (magenta), Hoechst (grey). Clec14a expression was tracked in vivo, a biotin-labelled monoclonal antibody (C2) raised against Clec14a was injected intraperitoneally and tissue was collected 24 h post injection. Scale bar is 200 µm. i. Region of interest with arrowheads (green) indicating areas where co-expression of all markers (white) is evident. ii. High magnification image demonstrating high expression of Clec14a within bud-like vessel protrusions and anastomotic arches. Scale bar is 10 µm. B Maximum intensity projection images show immunostaining of Mmrn2 (left image - green) and nuclei (Hoechst, right image - grey). Mmrn2 is located predominantly in the anatomical area normally covered by type-H vessels in the metaphysis (mp), moderate Mmrn2 expression is also observed in the region where type-L vessels reside (dp). White arrowheads indicate Mmrn2 staining on an arterial vessel (arterial vessel identified with reference to Kusumbe et al. 2014, Fig. 1 and extended data Fig. 2). White dashed line demarcates the growth plate metaphysis border and the periosteum. Abbreviations: gp-growth plate, mp-metaphysis, dp-diaphysis. Scale bars are 300 µm. C Expression of Clec14a and Mmrn2 in the bone stroma of adult mice (GSE128423). Left panel: t-SNE map of the stromal clusters in the bone coloured-coded according to their cluster name. Right panel: t-SNE maps reveal expression of H-type endothelial cell (EC) markers Pecam1 and Emcn alongside Clec14a and Mmrn2.