Definition of "vascular"

Reindeer are well suited to the taiga’s frigid winters. They can maintain a thermogradient between body core and the environment of up to 100 degrees, in part because of insulation provided by their fur, and in part because of counter-current vascular heat exchange systems in their legs and nasal passages.

2013 March, Nancy Langston, “Mining the Boreal North”, in American Scientist‎, volume 101, number 2, archived from the original on 13 April 2016, page 98