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 <WSD>then</WSD> by injecting the pulmonary artery and vein afterwards . 
Meaning of the word marked with <WSD> tags:  subsequently or soon afterward (often used as sentence connectors)