Fig. 3

Angiogenesis coupled with osteogenesis during intramembranous ossification: A Physiological VEGF levels maintain bone homeostasis. Low levels of VEGF disrupt osteoblast differentiation, while high levels increase osteoclast recruitment, leading to bone resorption; B Migration and proliferation of endothelial cells during bone repair, and secretion of BMP-2 and BMP-4.