Sentence:  It may be assumed that differences in ratings due to selection of <WSD>growth</WSD> centers from specific regions of the body will be small , according to existing tables of onset age and completion age for centers throughout the body . 
Meaning of the word marked with <WSD> tags:  (biology) the process of an individual organism growing organically; a purely biological unfolding of events involved in an organism changing gradually from a simple to a more complex level