Fig. S2.

Angled (A) and frontal (B) views of custom device for in vivo loading studies. Actuator (i) and load cell (ii) are in series beneath the platform and rectangular water bath (iii) to contain the foot. Upper loading contacts for three-point bending are part of the arm bracket assembly (iv) that wraps around the water bath, and is pulled from below to apply loads to the dorsal bone surface. The red stick shown in the apparatus represents the positioning of the MT3 in the device (v). Mice are under anesthesia while on the platform (vi). The entire apparatus sits on the stage of a multiphoton microscope.