Bilateral palatal shelves, which arise from the maxillary process of the first branchial arch, grow vertically down along the side of the tongue. At the precise developmental stage they rapidly reorient to a horizontal position above the dorsum of the tongue. The medial edge epithelia (MEE) of the opposing palatal shelves then adhere with each other to form a midline epithelial seam, which rapidly disappears to establish mesenchymal continuance and complete the process of palatal fusion. Formation of desmosomal junctions between MEEs of the both side provides a mechanism for palatal shelf adhesion. Desmosomes are intercellular adhering junctions that represent cell surface attachment sites for intermediate filaments. Desmosomes are localized in discrete spot-like trilaminar plaque structures of the lateral plasma membrane of adjacent epithelia cells. The purposes of this study were to characterize the desmosomal component (desmocollin1-3, desmoglein 1-3, desmoplakin) expression among oral, nasal epithelial cells and MEE cells in the wild type mouse embryo during secondary palate development period with laser capture microdissection (LCM, Pixcell II, Arcturus) and RT-PCR techniques and to observe the temporal and spatial pattern of desmosomal component with whole mount in situ hybridization. In normal development of mouse embryo, head skin, oral and nasal epithelial cells expressed all desmosomal component (desmocollin1-3, desmoglein 1-3, desmoplakin) during palatal fusion period. The MEE showed desmosome gene expression except desmocollin1 during critical time-point in the process of palatogenesis. As a further confirmation of the temporal and spatial expression of desmosomal gene, desmoglein 3 of vertical stage was used as an example of the distribution of desmosomal components genes. The result shows that desmoglein 3 is distributed in the oral, nasal, skin epithelial cells and MEE cells. TGF-b3 is expressed in E14 stage but not expressed in E13 and E18. The MEE is metabolically active with differential patterns of gene expression compared to the adjacent and continuous oral and nasal epithelia throughout the process of palatal fusion. These might not support apoptosis of the MEE but vitality of the MEE during palatal fusion.