The expression of GPR40 in periodontal tissues of participants without periodontitis and MetS, patients with periodontitis, MetS or both periodontitis and MetS. A. The negative control for immunohistochemical staining of GPR40 and CD36 in periodontal tissues. The tissue section incubated with normal human IgG as primary antibody was used as negative control. B. The GPR40 expression in periodontal tissues of control participants, patients with periodontitis, MetS, or both periodontitis and MetS. C. Quantification of GPR40 expression in periodontal tissues of control participants, patients with periodontitis (PD), MetS, or both PD and MetS.