CHARACTERIZATION OF THE EXTRACELLULAR-MATRIX DURING SOMITOGENESIS IN THE LONG-TAILED MONKEY (MACACA-FASCICULARIS)

The composition of the extracellular matrix (ECM) associated with somi togenesis (stages 10-14) in the long-tailed monkey (Macaca fasciculari s) was examined using peroxidase immunocytochemistry. A distinct tempo ral and spatial staining pattern was demonstrated for each component e xamined. Fibronectin (FN), laminin (LM) and hyaluronic acid (HA) were associated with the somite at each developmental stage, while no chond roitin sulfate (CS) staining was evident until stages 13/14. The basem ent membrane and matrix fibers linking the somites to the surrounding epithelia stained for FN, LM and HA. Localization of LM and HA between somite cells was observed at each stage, whereas FN and CS reactivity within the somitic tissue was only observed between sclerotome cells at stages 13/14. Whereas FN- and HA-positive fibers surrounded the uns egmented mesoderm, HA, and to a lesser extent LM, were located within the presomitic tissue. Comparisons are made with earlier studies condu cted in rodent and avian embryos which indicate that these ECM compone nts may play a regulatory role in primate somitogenesis.