Figure 3.

Vessel sprout, extension, and creation of new connection responding to chronic hypoxia. A representative image of the green fluorescent protein (GFP)-expressing endothelial cells (green) and sulforhodamine 101 (SR101)-labeled astrocytes (red), repeatedly imaged over prehypoxia (0d) to 21 days of hypoxia (21d). The new vessel (arrows) appeared at 7 days (7d) of hypoxia in the noncapillary regions around the center penetrating artery (arrowhead, see prehypoxia image), whereas the penetrating artery and parenchymal capillary apparently dilated after 7 days of hypoxia compared with prehypoxia. The newly formed vessel eventually connected with existing capillary (upper side in the image) up to 14 days (14d) of hypoxia. After forming the vessel connection, the shape of the new vessel normalized (i.e., slimed), and no stagnant blood cells were observed. After 14 to 21 days of hypoxia, the new vessel was extensively covered with processes from the neighboring astrocytes. For visual purposes, the maximum intensity projection was performed over depths of 45 to 70 μm from the surface (11 slices).