THE ASSOCIATION OF ACID MUCOPOLYSACCHARIDES WITH TRANSPOSITION OF THE PALATINE SHELF IN MOUSE EMBRYOS

Abstract

For clarifing the association of acid mucopolysaccharides with transposition of the palatine shelf in mouse (ddN strain) embryos, histochemical and macroscopic observations were made on the shelf prior to horizontal transposition. The latter observation was done by removing the tongue together with the lower jaw in Tyrode solution at 37°C. The results obtained were as follows : 1) The anterior portion of the shelf becomes quickly horizontal unchanging its shape, when the tongue is removd from the embryo with still vertically lying shelf on the 14th day of gestation. The posterior portion, however, remains in the original vertical position. The same phenomena are also seen in the embryo late on the 13th day of gestation.2) In the anterior portion, histochemically demonstrable acid mucopolysaccharides appear only just several hours before the normal transposition, which occurs near the middle of the 14th day of gestation. In the posterior, however, the same material appears in more earlier stages of the development. In either case, an increase of alkaline phosphatase precedes the appearance of acid mucopolysaccharides in the tissue.3) The transposition of the posterior portion is achieved by bulging the medial wall with simultaneously regressing the ventral wall of the shelf. The begins early and is completed in the middle on the 14th day.The following conclusions were drawn the above that : 1) Transposition of the shelf goes in two different ways; anteriorly by rotation and posteriorly by transformtion.2) Acid mucopolysaccharides seem to have no intimate correlation with the transposition, anteriorly, but to play an important role, posteriorly.3) It is interesting that appearance of alkaline phosphatase precedes alwsys that of acid mucopolysaccharides. The significance of this fact remains yet as a further problem.