Figure 7.

Abnormal fibril structure in mature Col5a1^Δten/Δten tendons. A and B: The Col5a1^Δten/Δten flexor digitorum longus (FDL) has larger and more heterogeneous fibrils than do the wild-type controls. In addition, fibrils assembled in collagen V–null tendons show aberrant structures (arrow). C: Histograms represent the distribution of fibril diameters in the FDL tendon of control and Col5a1^Δten/Δten mice. The Col5a1^Δten/Δten mice have broader distribution of the fibril diameters, with increased fibril numbers of both small-diameter and large-diameter fibrils. The diameter was measured in three different mice of each group, with seven images from each mouse. D: The mean fibril diameter is increased significantly in the FDL of Col5a1^Δten/Δten mice. E: The fibril density is decreased significantly in the FDL of Col5a1^Δten/Δten mice. The means ± SD, n = 21, and Student's t-test (D and E). All FDLs were from male mice at postnatal day 30. ^∗∗∗P < 0.001. Ctrl, control; Q, quartile.