The pulmonary arteriole.
D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging; D000818:Animals; D001160:Arterioles / Q000033:anatomy & histology; D002415:Cats; D002648:Child; D002675:Child, Preschool; D006651:Histocytochemistry; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008168:Lung / Q000098:blood supply*; D008875:Middle Aged; D009130:Muscle, Smooth / Q000033:anatomy & histology; D010503:Periodic Acid-Schiff Reaction