Localization of types I and III collagen and fibronectin in the developing mouse palatal shelves.

The detailed distribution of types I and III collagen and fibronectin was studied in the developing mouse palatal shelf using a double immunofluorescence technique. Just prior to palatal shelf elevation, type I collagen showed denser localization on the nasal side than on the oral side of the middle hard palate region. Such a distribution extended as far as the posterior hard palate region but not to the soft palate region. In type III collagen and fibronectin, this uneven distribution was not so distinct even in the middle hard palate region during the same period. The correspondence of the most conspicuous region of this distribution of extracellular matrix components with the region of first shelf elevation suggests that the extracellular matrix, especially type I collagen, participates in palate development.