Fig 2. Example of DOX bone labeling in 12-14wk old mice with different administration times.

Doxycycline (DOX) is a fluorescent tetracycline that can be administered to animals via drinking water and incorporates into actively mineralizing tissues. (A) Animals never exposed to DOX show no fluorescence even when imaged with a lengthy exposure (1000ms, no gain). (B) Animals exposed to DOX in utero until 3 weeks old have an intracortical band of labeled bone (exposure 500ms, no gain). (C) If DOX was administered until 8 weeks old, almost the entirety of the bone is labeled (exposure 500ms, no gain).