Sentence:  Our own studies in which bronchial artery pulmonary artery anastomoses were demonstrated , were accomplished by injecting the bronchial artery first with no pressure on the pulmonary artery or vein , and then by injecting the pulmonary artery and <WSD>vein</WSD> afterwards . 
Meaning of the word marked with <WSD> tags:  a blood vessel that carries blood from the capillaries toward the heart