Figure 2. Histopathological images of the traumatic ONFH rabbit model, and immunohistochemical staining and semi-quantitative analysis of vWF and CD105.

(A) Representative images of a section of femoral head including cartilage stained with H&E. Scale bar = 200 µm. In the injured femoral head, the number of empty lacunae increased and hematopoietic tissue diminished significantly, but cartilage did not exhibit any obvious pathological changes. Immature fibrotic tissue and appositional bone formation were observed under the cartilage from 3 days after trauma, followed by an increase in the number of OBs 2 weeks later. a. empty lacuna; b. immature fibrotic tissue; c. appositional bone formation; d. OBs. (B) Bar graphs represent the ratio of bone marrow cells to the area of bone marrow (a), the ratio of empty lacunae to the area of trabeculae (b), thinning trabeculae (c) and grey scale (d), respectively. (C) Immunohistochemical assays of vWF expression. Scale bar = 50 µm. (D) Blood vessels were counted according to positive staining of vWF in combination with appropriate vessel structure. Following trauma, the structure of the blood vessels became increasingly compromised and the number of blood vessels decreased. Arrows = microvessels or arteries. (E) Immunohistochemical assays of vWF expression. Scale bar = 20 µm. (F) Bar graphs represent the expression density of CD105 as unit area of bone marrow or unit area of bone trabeculae. The expression of CD105 until 3 weeks after trauma suggested the presence of revascularization in the injured femoral head. N: normal group; 3 d, 1 w, 2 w, 3 w: 3 days, 1 week, 2 weeks, 3 weeks post-trauma, respectively. Quantification was based on at least 10 fields per section. *P<0.05 vs. normal group.