Mmp2 deficiency affects fibrillar collagen remodeling in vivo. TEM of in vivo lymphangiogenesis induced by thermal cauterization of the cornea (A-F) and in lymphangioma (G-J), in WT (A,C,E,G) and Mmp2 KO mice (B,D,F,H-J). (A-C) LECs form long processes (p) and contain intracellular vesicles (arrow). The ECM is extensively remodeled leading to numerous gaps between cells (#). (B-D) In the absence of Mmp2, LECs are surrounded by dense matrix and parallel lumens are often seen (B) in neoformed lymphatic vessels (Lu). (E-F) Higher magnification of the extensively remodeled collagen matrix (#) in WT mice (E), but reminiscent in KO mice (F). (G-H) Neoformed lymphatic vessels in lymphangioma surrounded by processed matrix (#) in WT mice (G), but dense matrix (*) in KO mice (H). (I-J) Lymphatic capillaries forking (arrows) around dense matrix (*) in Mmp2-deficient mice. Bars represent 5 μm (A-D), 1 μm (E,G,H) and 2 μm (F,I,J).