Sentence:  Each cell except the last in the chain also contains the address of the Y-cell that is the next <WSD>element</WSD> of the chain ; the absence of such a link in the last cell indicates the end of the chain . 
Meaning of the word marked with <WSD> tags:  an artifact that is one of the individual parts of which a composite entity is made up; especially a part that can be separated from or attached to a system