The occurrence of a new mutation affecting cartilage and bone in mice is reported. The gene is lethal, shows autosomal recessive inheritance, and has high penetrance. It is not allelic to shorthead and probably not to phocomelia or achondroplasia . It results in a foreshortened face, cleft palate, defective trachea, and shortened long bones with flared metaphyses. Chondrocytes of epiphyseal cartilage from the mutant are not aligned in columns, and there is a decrease in the usual staining of the cartilage matrix. Electron microscope observations show large, wide collagen fibrils with "native" banding in the matrix of mutant cartilage, which are not present in normal cartilage. Possible explanations for the expression of this genetic disorder of cartilage development are put forward.

Electron microscopic observations on chondrocytes from rabbit ear cartilage 72 hours after papain has been given intravenously show that many vacuoles in the Golgi apparatus contain a material with a speckled appearance. Some Golgi vacuoles also contain a material with a banded pattern which can be identified as a collagen. The significance of this observation is discussed.