Selective development of one cone photoreceptor type in retinal organ culture

The authors have established an organ culture method in which the the postnatal development and the structural integrity of the mouse retina can be maintained for at least 6 weeks. Additionally, they have examined the emergence and in vitro morphogenesis of the photoreceptors and the development of insoluble components of the interphotoreceptor matrix.

Neural retinas and retinal pigment epithelia from 48-hour-old C3H ++/++ mice were cultured. At various ages, the tissues were fixed and cryosectioned or wholemounted. Photoreceptor development was studied by immunocytochemistry with visual pigment antibodies and by lectin cytochemistry. The ultrastructure of the photoreceptors was studied by electron microscopy.

Immunopositive rods and short-wave sensitive cones were detectable as early as 3 days after explantation. From this time on, matrix domains around cones were also identifiable and labelled with peanut agglutinin lectin. However, the antibody specific to the middle-wave sensitive cone pigment failed to recognize any cones throughout the 6-week culture period.

Both basic photoreceptor types appeared and developed in this organ culture system according to a timetable comparable to normal in vivo development. Surprisingly, under these circumstances, one of the two cone pigments was not expressed by any photoreceptors.