n 1 a  :  the act of describing a thing by giving its differentia  b  :  the enhancement of microscopically visible differences between tissue or cell parts by partial selective decolorization or removal of excess stain (as in regressive staining)  c  :  the development of a discriminating conditioned response with a positive response to one stimulus and absence of the response on the application of similar but discriminably different stimuli  2 a  :  modification of different parts of the body for performance of particular functions : also  :  specialization of parts or organs in the course of evolution  b  :  the sum of the developmental processes whereby apparently unspecialized cells, tissues, and structures attain their adult form and function - compare DETERMINATION2   .
 
 
 
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