adj 1  :  situated within but not restricted to or characteristic of a particular organ or tissue - used esp. of fibrous tissue  2  :  affecting the interstitial tissues of an organ or part < hepatitis>   3  :  occurring in the part of a fallopian tube in the wall of the uterus < implantation>  < pregnancy>  in*ter*sti*tial*ly adv 
 
 
 
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