Differentiation

1 The process by which cells become progressively more specialized; a normal process through which cells mature. This process of specialization for the cell comes at the expense of its breadth of potential. Stem cells can, for example, differentiate into secretory cells in the intestine. 2 In cancer, differentiation refers to how mature (developed) the cancer cells are in a tumor. Differentiated tumor cells resemble normal cells and tend to grow and spread at a slower rate than undifferentiated or poorly differentiated tumor cells, which lack the structure and function of normal cells and grow uncontrollably.

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1. The acquisition or possession of one or more characteristics or functions different from that of the original type. SYN: specialization (2). 2. SYN: differential diagnosis. 3. Partial removal of a stain from a histologic section to accentuate the staining differences of tissue components.

- correlative d. d. due to the interaction of different parts of an organism.

- echocardiographic d. the processing of a signal so that the output depends upon the rate of change of the input; e.g., it will display changes in amplitude but will reduce the duration of the waveform.

- invisible d. SYN: chemodifferentiation.

- pressure pulse d. the processing of a pressure pulse signal so that the output depends upon the rate of change of the input, yielding dP/dt (pressure) or, for noninvasively recorded pulses, dD/dt (rate of change of displacement).

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dif·fer·en·ti·a·tion -.ren-chē-'ā-shən 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 DETERMINATION (2)

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n.

1. (in embryology) the process in embryonic development during which unspecialized cells or tissues become specialized for particular functions.

2. (in oncology) the degree of similarity of tumour cells to the structure of the organ from which the tumour arose. Tumours are classified as well, moderately, or poorly differentiated: well-differentiated tumours appear similar to the cells of the organ in which they arose; poorly differentiated tumours do not. Such classification is often of prognostic significance.

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dif·fer·en·ti·a·tion (dif″ər-en″she-aґshən) 1. the distinguishing of one thing or disease from another. 2. the act or process of acquiring completely individual characters, as occurs in the progressive diversification of cells and tissues of the embryo. 3. increase in morphological or chemical heterogeneity.