Sentence:  <WSD>Sections</WSD> of sweet clover stem and root tumors were treated with 1 : 10 solution of * * f for 30 minutes , washed in buffered saline for 15 minutes , stained with * * f for 30 minutes , and washed for 15 minutes in PBS . 
Meaning of the word marked with <WSD> tags:  one of several parts or pieces that fit with others to constitute a whole object