Isolation of human fetal cones

Purpose. To describe a method for isolating a monolayer of human fetal cone photoreceptors and to compare their structure and ultrastructure before an d after preparation. Methods. Eyes from human fetuses (fetal week 20 to 24) were dissected and t he neural retina of the developing fovea identified, cut out and placed on 10% gelatin. A VISX Star(TM) excimer laser was used to remove the inner ret inal layers. The isolated cone monolayers were cultured for 18 hours and co mpared with untreated retinas by light microscopy and transmission electron microscopy. Results. Excimer laser ablation removed the inner nuclear and ganglion cell layers leaving a monolayer of fetal cones. These cones survive in culture for at least 18 hours. The laser ablation disorganized the ultrastructure o f the synaptic pedicles of these cones, left their plasma membranes intact. Conclusions. The developing central retina of human fetal eyes provides a s ource of fetal cones, which can be isolated from inner retinal cells using the excimer laser. Such a monolayer of human fetal cones may be useful for transplantation or biochemical studies.