抄録
The distribution of certain basement membrane (BM) components was examined using indirect immunofluorescence and autoradiography during the facial development in rat embryos. At the onset of the nasal placode, fibronectin, laminin, type IV collagen and BM proteoglycan were found to be present especially at the epithelial-mesenchymal interface (BM) of the nasal placode, although the BM of the presumptive nasal placode was stained and labeled weakly in earlier stages. In later stages when the nasal processes had been formed, the strongly stained and labeled area of those four BM components was limited to the BM in the apical parts of the nasal processes.
The incorporation of3H-thymidine was also examined to clarify the relation between the mesenchymal cell proliferation and the changes in the distribution of the BM components during the invagination of the nasal placode and the development of the nasal processes. Many labeled cells were detected in the region of condensed mesenchymal cells beneath the nasal placode. At the advanced stages, labeled cells were much more decreased in the basal area of the invaginating nasal pit compared to the apical regions of the nasal processes.
The changes, which were observed in the distribution pattern of the BM components and in the rate of the mesenchymal cell proliferation during the facial development, appear to be closely associated with the regulation of the morphogenetic change in tissue form.
