Sentence:  In the experimental animal and in man gross deficiency in dietary iodine causes thyroid hyperplasia , hypertrophy and increased thyroid <WSD>activity</WSD> ( Money , Rall and Rawson , 1952 ; Stanbury , Brownell , Riggs , Perinetti , Itoiz , and Del Castillo , 1954 ) . 
Meaning of the word marked with <WSD> tags:  an organic process that takes place in the body