Biochemistry of Developing Eyes

AN attempt has been made to find the cells of origin and the time of origin during development of the vitreous hyaluronic acid. The adult vitreous body of those species so far examined seems to owe its characteristic jelly-like properties to the presence of small amounts of an insoluble collagen-like protein laid down in fibrous lamellae and a low concentration of hyaluronic acid. Earlier work with adult rabbits (Pirie, 1949) has shown that aggregated hyaluronic acid can be regenerated in the vitreous body after removal by hyaluronidase. It therefore seemed possible that, in the young, rapidly enlarging eye, histochemical tests might be able to show which cells produced hyaluronic acid and at what stage in development this took place. The time of production could then be checked by chemical analysis of the extracted vitreous body. Meyer (1947) has suggested that hyaluronic acid is secreted by the ciliary body. We can say at once that we have no clear evidence on the origin of hyaluronic acid within the vitreous body; in pursuing this problem, however, we have collected information on changes in the chemical composition of the developing vitreous body in the young rabbit as well as histochemical evidence for the presence of a granular material in the retina at a certain stage of development which stains by the method for detecting polysaccharides (Hotchkiss, 1948). The evidence is briefly presented, as it may be of interest to, and save the the time of, others working on similar problems.