The association of mucopolysaccharides with morphogenesis of the palate and other structures in mouse embryos.

A C I D mucopolysaccharides have been postulated to occur in the palatine shelves of mouse embryos on the basis of metachromatic staining with toluidine blue (Walker & Fraser, 1956), and this idea has since been supported by results from radioautography with S (Larsson, Bostrom, & Carlsoo, 1958). It was not known which structural component of the tissue contained this substance, but, since aldehyde fuchsin-positive material existed in the same area, the possibility was raised that the component was a network of elastic fibres (Walker & Fraser, 1956). The first purpose of the present paper is to describe further histochemical and radioautographic investigations of this problem, supplemented by electron microscopic observations of palatine shelf tissue. Numerous sites of S incorporation have been identified in embryos of various ages, including embryos too young to contain cartilage (Dziewaitkowski, 1958). Very little was concluded from such studies concerning the role of sulphated acid mucopolysaccharides other than noting their characteristic presence as a component of cartilage and bone. In view of the apparent association between sulphated acid mucopolysaccharides and palate development (Walker, 1960), it seemed desirable to gain a broader perspective on the possible significance of this substance in morphogenesis, so that the experiments described in the present paper were extended secondarily to include earlier stages of embryonic development.