A 72-year-old woman visit the emergency department with diabetes develops an ulcer on her right leg (shown in the figure). The ulcer bed is covered with granulation tissue. Which of the following are the principle cellular components found in the bed of this wound?
1.Myofi broblasts and eosinophils
2.Fibroblasts and endothelial cells
3.Neutrophils and lymphocytes
4.Plasma cells and macrophages
5.Smooth muscle cells and merkel cells
Solution
Granulation tissue has two major components: i) cells and ii) proliferating capillaries. The cells are mostly fibroblasts, myofibroblasts, and macrophages. Fibroblasts and myofibroblasts derive from
mesenchymal stem cells. Capillaries arise from adjacent blood vessels by division of endothelial cells in a process termed angiogenesis. Macrophages are a principal source of growth factors and are recognized for their phagocytic functions. Granulation tissue is fluid laden, and its cellular constituents supply antibacterial antibodies and growth factors. Once repair has been achieved, most of the newly formed capillaries are obliterated and then reabsorbed, leaving a pale avascular scar. Although the other inflammatory cells listed may be found in this healing wound, they do not constitute the principal components of granulation tissue.