Initial uptake and localization of FITC labeled HPMA copolymer-Asp8 conjugate in bone compared with the uptake of tetracycline. (A) The conjugate preferentially incorporates in scalloped-appearing eroded surfaces in cancellous bone (white arrows); tetracycline (yellow label) is incorporated onto active bone mineralization surfaces. (B,C) Stained (B) and unstained (C) section of the same region of the proximal tibial growth plate and primary spongiosa. Tetracycline (yellow label) incorporated into the mineralizing zone of the growth plate (C, orange arrowhead) as expected, whereas HPMA copolymer-Asp8 conjugate (green label) localized in the resorption areas of the primary spongiosa (C, white arrows). Magnifications: A=150x; B,C=125x. Reprinted with permission from reference [59].