Diagram showing the position of the pecten oculi within a bird eye
Thepecten orpecten oculi is acomb-like structure ofblood vessels belonging to thechoroid in theeye of abird. It is a non-sensory,pigmented structure that projects into thevitreous humor from the point where theoptic nerve enters theeyeball.[1] The pecten is believed to both nourish theretina and control thepH of the vitreous body.[2] High levels ofalkaline phosphatase activity in the pecten oculi have been linked to the transport of nutrient molecules from the highly vascularized choroid into vitreous and retinal cells, thus nourishing the eye.[3] It is present in all birds and somereptiles.[4]
In thevertebrate eye, there are blood vessels in front of the retina, partially obscuring the image. The pecten helps to solve this problem by greatly reducing the number of blood vessels in the retina and leading to the extremely sharp eyesight of birds such ashawks.[5] The pigmentation of the pecten is believed to protect the blood vessels against damage fromultraviolet light.Stray light absorption by melanin granules of pecten oculi is also considered to give rise to small increments in temperature of pecten and eye; this may offer increased metabolic rate to optimize eye physiology in low temperatures at high-altitude flights.[6] The structure varies across birdspecies and isconical in thekiwi, vaned in theostrich andpleated in most other birds.[7]
^Walls (1942),The Vertebrate Eye and its Adaptive Radiation, Hafner Publishing,ISBN0-02-854430-7{{citation}}:ISBN / Date incompatibility (help)
^Kiama, S. G.; Maina, J. N.; Bhattacharjee, J.; Weyrauch, K. D. (2001). "Functional morphology of the pecten oculi in the nocturnal spotted eagle owl (Bubo bubo africanus), and the diurnal black kite (Milvus migrans) and domestic fowl (Gallus gallus var.domesticus): a comparative study".Journal of Zoology.254 (4):521–528.doi:10.1017/s0952836901001029.
^Kiama, S G; Bhattacharjee, J; Maina, J N; Weyrauch, K D (December 1994), "A scanning electron microscope study of the pecten oculi of the black kite (Milvus migrans): possible involvement of melanosomes in protecting the pecten against damage by ultraviolet light",Journal of Anatomy,185 (Pt 3):637–642,PMC1166670,PMID7649799
