Summary
The median ocellus of Limulus consists of irregular groups of large photoreceptor cells which form a cup-shaped retina around the ocellar lens. Each group is surrounded and penetrated by guanophores and glia. The photoreceptor cells have extensive rhabdomeric regions, both along infoldings of cell membranes and between cells. Five-layered junctions occur between rhabdomeric microvilli. An occasional arhabdomeric (AR) cell is associated with a group of photoreceptors. Fine dendritic branches of the AR cell penetrate the rhabdomeric regions and form five-layered junctions with photoreceptor rhabdomeres. Axons of photoreceptor cells, and of at least some AR cells, gather at the proximal side of the cup to form an optic nerve.
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Supported in part by NIH EY00312 and EY00377.
We would like to thank Dr. W. K. Stell, Dr. A. C. Bell, and Dr. W. H. Fahrenbach for their helpful discussions.
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Jones, C., Nolte, J. & Brown, J.E. The anatomy of the median ocellus of Limulus . Z. Zellforsch. 118, 297–309 (1971). https://doi.org/10.1007/BF00331188
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DOI: https://doi.org/10.1007/BF00331188