Human salivary gland morphogenesis: myoepithelial cell maturation assessed by immunohistochemical markers Renata Fraga Ianez, 1 Marcilei E Buim, 1 Claudia M Coutinho-Camillo, 1 Regina Schultz, 2 Fernando A Soares, 1,3 & Silvia Vanessa Lourenc ¸o 3 1 Department of Surgical Pathology, Hospital A.C. Camargo, 2 Department of Surgical Pathology, Hospital das Clı ´nicas, Medical School, and 3 Department of General Pathology, Dental School, University of Sa ˜o Paulo, Sa ˜o Paulo, Brazil Date of submission 29 October 2009 Accepted for publication 14 December 2009 Ianez R F, Buim M E, Coutinho-Camillo C M, Schultz R, Soares F A & Lourenc ¸o S V (2010) Histopathology 57, 410–417 Human salivary gland morphogenesis: myoepithelial cell maturation assessed by immuno- histochemical markers Aims: Myoepithelial cells are important components of salivary gland structure, aiding the expulsion of saliva from acinar lobules. The aim was to evaluate the expression of smooth muscle actin (SMA), calponin, caldesmon, CD10, CD29, S100 protein, glial fibrillary acidic protein (GFAP) and p63 in myoepithelial cells during salivary gland morphogenesis to understand the maturation process of these cells and their possible use in the diagnosis of salivary gland lesions. Methods and results: Major and minor human salivary glands at various stages of development, derived from fetuses at 8–26 weeks of gestation, were studied immunohistochemically. Fully developed salivary glands were used as controls. The protein p63 was present in all stages of salivary gland morphogenesis from initial bud to terminal bud stage. CD29, S100 and calponin were detected increasingly as salivary gland structure matured and in fully developed salivary gland. Proteins GFAP, CD10 and caldesmon were not observed in myoepithelial cells of salivary glands. Conclusions: The proteins SMA, calponin, CD29, S100 and p63, which are present from the earliest stages of salivary gland maturation, are valuable myoepithelial markers but, although very specific, are not exclusive markers for this cell type. Keywords: human, morphogenesis, myoepithelial cells, salivary gland Abbreviations: GFAP, glial fibrillary acidic protein; SMA, smooth muscle actin Introduction Similar to other organs, the formation of the salivary gland involves coordination of morphogenetic mecha- nisms, including regulated changes in cell shape and gene expression, and directed cell migration leading to a fully developed gland with important secretory functions. Morphologically, all salivary glands develop similarly, starting with the proliferation of a solid cord of cells from the epithelium of the stomatodeum into the underlying ectomesenchyme. This cord of cells extends deeply into the ectomesenchyme and branches extensively, forming channels with secretory end pieces. 1,2 In this glandular structure, myoepithelial cells are important components, though their partici- pation during the stages of development is still largely unknown. Myoepithelial cells are closely related to the secretory units and proximal ducts, being located between the basal lamina and the acinar or ductal cells. The distribution of myoepithelial cells varies considerably between types of glands and even in the same gland during the course of development. The morphology of these cells may vary and their role includes contraction when the secretory function of the gland is stimulated, compressing and strengthening the cells of the glan- dular parenchyma and assisting the expulsion of saliva. Address for correspondence: Dr S V Lourenc ¸o, Faculdade de Odontologia da Universidade de Sa ˜o Paulo, Av. Prof. Lineu Prestes, 2227, Sa ˜o Paulo-SP, CEP: 05508-000, Brazil. e-mail: silvialourenco.70@terra.com.br Ó 2010 Blackwell Publishing Limited. Histopathology 2010, 57, 410–417. DOI: 10.1111/j.1365-2559.2010.03645.x