Sentence:  In the large majority of normal patients, the <WSD>hila</WSD> appear equal in size on frontal radiographs; comparison of the two <WSD>hila</WSD> is helpful in patients with a unilateral abnormality. 
Meaning of the word marked with <WSD> tags:  A depression or fissure through which ducts, nerves, or blood vessels enter and leave a gland or organ; a porta.