Fig. 1.

Hypoxic-induced changes in brain capillary density, as assessed by CD31 immunohistochemistry. Frozen sections of brainstem or cerebral cortex taken from mice exposed to normoxic conditions or 4, 7 or 14-day hypobaric hypoxia were immunostained with a CD31 monoclonal antibody as described in Experimental methods. Scale bar=100 μm. Note that over a 14-day period, hypobaric hypoxia induced a gradual increase in capillary density in both regions examined.