Distribution of glycosaminoglycans in the developing facial region of mouse embryos.

Synthesis and distribution of glycosaminoglycans in the developing facial region of mouse embryos were investigated during stages of development when the embryonic facial processes form and expand. Facial regions of 11th and 12th day embryos were either 1) labeled with 3H-glucosamine and newly synthesized glycosaminoglycans determined on the basis of specific enzyme sensitivity, or 2) sectioned and stained with Alcian Blue coupled with enzyme digestion in order to localize glycosaminoglycans. On the basis of enzyme sensitivity over half of the newly synthesized glycosaminoglycans during this time period were identified as hyaluronate, with only 12-15% representing chondroitin sulfate. Hyaluronate was found to be the primary component of the extracellular matrix. Basal laminae exhibited prominent chondroitin sulfate staining and also appeared to contain hyaluronate and heparan sulfate. It is suggested that hyaluronate may play a structural role in maintaining the shape and orientation of the facial processes.