The morphology of the eyes of Limulus

Summary The dioptric apparatus of the Limulus compound eye is composed of the corneal cuticle with its internally projecting cuticular cones and the specialized underlying epidermis. The latter is composed of three distinct cell types. The guanophores, located between cuticular cones, contain guanine as a reflecting pigment. The distal pigment cells, which clothe the sides of the cuticular cones and form a sheath around the underlying ommatidium, contain massive bundles of microtubules, abundant pigment droplets and a large Golgi system. The cone cells are positioned between the flattened tip of the cuticular cone and the apex of the ommatidium. They serve to anchor the retinula cells to the cuticle and, by virtue of long processes along the periphery of the rhabdome, perform a glial function with respect to the interaction of adjacent retinula cells. The geometry and fine structure of the dioptric apparatus provide supporting evidence for the wide angle of acceptance and lack of polarized light perception by the ommatidia.This study constitutes publication No. 288 from the Oregon Regional Primate Research Center, supported in part by Grants FR 00163 and NB 07717-01 from the National Institutes of Health and in part by a Bob Hope Fight For Sight Grant-in-Aid of the National Council to Combat Blindness, Inc. The author wishes to thank Mrs. Audrey Griffin for patient and excellent technical assistance.