Which of the following statement(s) is/are true about the role of macrophages in the wound healing process?

a. Macrophages are the dominant cell type during the inflammatory phase of wound healing 

d. Macrophages are a source of a number of humoral factors essential for wound healing

Within three or four days after injury, macrophages become the dominant cell type in the inflammatory phase of wound healing. The role of macrophages is not limited only to phagocytosis. In addition, macrophages are the source of more than 30 different growth factors and cytokines. These growth factors induce fibroblast proliferation, endothelial cell proliferation (angiogenesis), extracellular matrix production, and recruit and activate additional macrophages. The result is the induction of a wound healing amplification cycle as growth factors recruit macrophages and elicit additional growth factor release. Experimental studies in which antibodies, which either destroy PMNs or block certain aspects of their function, have shown that wounds heal normally, but that healing is significantly impaired without functional macrophages. These studies confirm the dominant role of the macrophage and the inflammatory phase of wound healing