Figure 4

Delayed bone mineralization in ERp44 KO mice by means of histological staining of the femoral growth plate

(A) Hematoxylin and eosin staining of the growth plate at 4 and 11 weeks of age (top and bottom, respectively). Growth plates (GP) are larger in both Het and KO with respect to WT control mice at 4 weeks of age. E, epiphysis; D, diaphysis. Scale bars, 200 μm.

(B) Example of growth plate in Stevenel’s/Van Gieson (SVG) staining at higher magnification (bone in red color: asterisks; mineralized cartilage in pink color: arrowheads; cartilage in violet color: arrows; bone marrow in brown color: hashtag) to show details of epiphyseal growth plate components.

(C) Example of growth plate in Safranin-O/light green section at higher magnification (bone in light blue color: asterisk; cartilage in red color: arrowhead; bone marrow in dark blue color: hashtag). E, epiphysis; GP, growth plate; D, diaphysis. Scale bars, 25 μm.

(D) SVG quantifications at 4 weeks of age (n = 6, two WT: 2 males, bone 51.8% ± 16.1%, CC 21.8% ± 9.6%; two Het: 2 males bone 51.7% ± 8.2%, CC 15.3% ± 1.1%; two KO: 2 males, bone 43.4% ± 8.4%, CC 17.3% ± 10.0%) and Saf-O quantification (n = 6, two WT: 2 males, 17.3% ± 4.6%; two Het: 2 males, 30.0% ± 4.6%; two KO: 2 males, 23.0% ± 8.4%). SVG quantifications at 11 weeks of age (n = 6, two WT: 2 males, bone 64.0% ± 10.1%, CC 32.2% ± 12.9%; two Het: 2 males, bone 52.0% ± 6.3%, CC 42.1% ± 11.3%; two KO: 2 males, bone 38.3% ± 5.2%, CC 24.1% ± 10.8%) and Saf-O quantification (n = 6, two WT: 1 male and 1 female, 17.6% ± 2.3%; two Het: 1 male and 1 female, 30.8% ± 3.8%; two KO-1 male and 1 female, 36.2% ± 10.5%). Average ± SD, One-way ANOVA with Dunnett’s multiple comparison test (∗p < 0.05, ∗∗p < 0.01), three images were analyzed for each mouse.