Paired vessels in the spinal cord of Rhesus monkey and cat

In the spinal cord of the rhesus monkey and of the cat paired vessels near the central canal are described. These paired vessels, consisting of one artery and one vein, are enveloped by a common glial sheath. In some Virchow-Robin's spaces two arteries and two veins can be observed. The physiological significance of this morphological feature is briefly discussed.