Radioisotopes for research into vitreous and zonule.

A survey of the use of radioisotopes for research into the vitreous and the zonule is presented. gamma-Rays emitting isotopes are useful for the investigation of transport and diffusion of substances, while 3H-thymidine is the substance of choice for the investigation of cell kinetics. The formation of the vitreous and the zonule during and after embryonal development can be studied by histoautoradiography using labelled precursors of collagen and aminoglycans. Cell kinetic investigations shows that the cells usually found in the vitreous are macrophages which have migrated into the eye. Therefore the existence of a specific vitreous cell is unlikely. The development of the zonule can be readily traced by histoautoradiography which shows that it is neither topographically nor temporally related to regression of the primary vitreous. The incorporation of cystine and glucose into the zonular fibers is of special interest. This suggests that the zonular fibers are not made up of normal collagen; they may consist of some sort of procollagen which is perhaps secreted by the ciliary epithelium.