Twist1- and Twist2-Haploinsufficiency Results in Reduced Bone Formation
Figure 2
Histological examination of Twist1flox/+; Twist2Cre/+ mice.
(A–B) Femur sections of 6-day-old control and Twist1flox/+; Twist2Cre/+ mice were stained with H&E. The Twist1flox/+; Twist2Cre/+ mice displayed reduced metaphyseal trabecular bone (A, red arrows) and a decreased thickness of the periosteum (B, blue arrows) and cortical bone (B, red arrows). (C) TRAP staining of femur sections of 6-day-old control and Twist1flox/+; Twist2Cre/+ mice. Note that the osteoclasts (red arrows) appeared to be similar in size and distribution in the control and Twist1flox/+; Twist2Cre/+ mice. The osteoclast densities were 0.55±0.06/0.01 mm2 in the controls (n = 5) and 0.60±0.02/0.01 mm2 in the Twist1flox/+; Twist2Cre/+ mice (n = 5, P>0.05). (D–F) In situ hybridization analyses (signal in blue) of the transcripts of Alp (D), Ocn (E) and Dmp1 (F) in the femurs of one-week-old control and Twist1flox/+; Twist2Cre/+ mice. (G, H) Immunohistochemical analyses (signal in brown) of the osterix (G) and biglycan (H) protein levels in the femurs of the 6-day-old control and Twist1flox/+; Twist2Cre/+ mice. Scale bar = 100 µm.