n pl 1  :  numerous small vessels that arise from the terminal branches of arteries supplying the intestine, encircle the intestine, and divide into more branches between its layers  2  :  hairpin-shaped vessels that arise from the arteriole leading away from a renal glomerulus, descend into the renal pyramids, reunite as they ascend, and play a role in the concentration of urine .
 
 
 
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