CHANGES IN THE DISTRIBUTION OF EXTRACELLULAR-MATRIX COMPONENTS DURINGNEURAL CREST DEVELOPMENT IN XIPHOPHORUS SPP EMBRYOS

The changes in distribution of chondroitin sulfate proteoglycans (CSs) and fibronectin (FN), two major components of the extracellular matri x (ECM), are described during the development and migration of neural crest cells in two Xiphophorus species of fish, X. helleri (swordtail) and X. maculatus (platyfish), using immunohistochemistry. A detailed description of the developmental changes in HNK-1-positive ECM compone nts is also provided and compared with those of CSs and FN. HNK-1 anti gen was also used as a marker for the neural crest cells. Weak stainin g for CSs, FN, and HNK-1-positive ECM was present in the neural crest cell migration pathways prior to migration of the cells. The level of staining increased dramatically during migration of these cells and de creased again after migration was nearly completed. Staining for CSs w as more widespread than staining for FN, while the HNK-1 staining patt ern was more clearly restricted to the migratory pathways than those s een with the other two antibodies. The correlation between the spatiot emporal relationship of these ECM components and the segregation and m igration of neural crest cells suggests that these ECM molecules may b e involved in both initiating and guiding the migration of neural cres t cells in these fish. The HNK-1-positive ECM may play a more critical role than CSs and FN.