Summary
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1.
The fine structure of the eye has been studied in three species of peripatus (Phylum Onychophora): Perpatonder novaezealandiae from New Zealand and Epiperipatus braziliensis and Macroperipatus geayi from Panama.
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2.
The retina contains two kinds of cells: pigmented (supportive) and sensory. Each sensory cell bears at its distal end a long process from which extend orderly arrays of straight microvim.
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3.
Rudimentary cilia are found at the bases of the receptoral processes, enclosed in extracellular spaces which suggest that the cilia became recessed into the sensory cells in development. The photoreceptor of peripatus is classified as rhabdomeric rather than ciliary in type.
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4.
The photoreceptors of peripatus resemble those of annelids in some features and those of arthropods in other respects.
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5.
Each sensory cell possesses an axon which runs through the collagenous capsule of the eye and to the brain via the optic nerve.
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6.
The cornea consists of one or two cuticular layers, an outer cellular layer which is a continuation of the epidermis and which secretes the corneal cuticle, and an inner layer of cells which is continuous with the retina and which secretes the lens, a large finely granular body. Between the cellular layers is a narrow band of collagen.
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The authors acknowledge with appreciation a grant-in-aid of research from the United States Public Health Service, the assistance of Mrs. Donald B. Hess, Miss Jean Leutwiler, and Mrs. Emily E. Reid, and a critical reading of the paper by Drs. Edith Krugelis MacRae, Dorothy R. Pitelka, and Ralph I. Smith.
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Eakin, R.M., Westfall, J.A. Fine structure of the eye of peripatus (Onychophora). Zeitschrift für Zellforschung 68, 278–300 (1965). https://doi.org/10.1007/BF00342434
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DOI: https://doi.org/10.1007/BF00342434