Sentence:  These <WSD>cells</WSD> were thawed at 37 ` C for 30 min and were deglycerolized by alternately centrifuging and mixing with descending concentrations of glycerol solutions ( 20 , 18 , 10 , 8 , 4 and 2 % ) . 
Meaning of the word marked with <WSD> tags:  (biology) the basic structural and functional unit of all organisms; they may exist as independent units of life (as in monads) or may form colonies or tissues as in higher plants and animals