TSP-1 decreases the number of inosculated, patent MVs in ex vivo implants. Isolated MVs from VE-cadherin-YFP mice were resuspended in matrigel + BSA (A) or recombinant TSP-1 (B), implanted subcutaneously in TSP-1−/− mice, and allowed to inosculate with host vasculature for 30 days. Images are representative of three independent experiments. Texas-Red-LEA is red, YFP-expressing ECs are yellow. Isolated MVs from WT (C) or TSP-1−/− (D) mice were implanted into hosts with their identical, respective genotypes. Images are representative of three independent experiments; FITC-LEA is green and Hoechst is blue. (E) The absence of TSP-1 increases MV diameter, and the addition of exogenous TSP-1 reduces MV diameter. Data are means from at least seven 20× images per condition per experiment ± SEM (** p < 0.01).