The aim of the present research was to trace CD34+ stromal fibroblastic cells (CD34+ SFCs) in the palatal connective tissue harvested for muco-gingival surgical procedures and in granulation tissues from periodontal pockets using immunohistochemical and transmission electron microscopy. Immunohistochemical analysis targeted the presence of three antigens: CD31, α-smooth muscle actin (α-SMA), and CD34. In the palate, CD31 staining revealed a colored inner ring of the vessels representing the endothelium, α-SMA+ was located in the medial layer of the vasculature, and CD34 was intensely expressed by endothelial cells and artery adventitial cells (considered to be CD34+ SFCs). Granulation tissue showed the same pattern for CD31+ and α-SMA, but a different staining pattern for CD34. Ultrastructural examination of the palatal tissue highlighted perivascular cells with fibroblast-like characteristics and pericytes in close spatial relationship to endothelial cells. The ultrastructural evaluation of granulation tissue sections confirmed the presence of neovasculature and the inflammatory nature of this tissue. The present study traced the presence of CD34+ SFCs and of pericytes in the palatal connective tissue thus highlighting once more its intrinsic regenerative capabilities. The clinical and systemic factors triggering mobilization and influencing the fate of local CD34+SCFs and other progenitors are issues to be further investigated.
