Histological analyses of long bones.

<p>A, C, E, G are H & E stained histological sections of <i>R26^floxneoWnt4</i> heterozygous controls; and B, D, F, H are <i>R26^floxneoWnt4; Col2a1-Cre</i> mutants. A, B, 15.5 dpc tibiae. C, D, 15.5 dpc femurs. The formation of the primary ossification center (arrows) was delayed in both tibiae and femurs of the mutant in comparison to controls. E, F, 2-week-old tibiae, showing development of the secondary ossification center (black arrow) in the control but only chondrocyte hypertrophy (black arrow) in the mutant that also had a disorganized growth plate (red arrow). G, H, 9-month-old mutant tibia with little bone marrow (G) filled with adipocytes (H, arrow).