Retinal photoreceptors and visual pigments in Boa constrictor imperator.

@article{Sillman2001RetinalPA,
  title={Retinal photoreceptors and visual pigments in Boa constrictor imperator.},
  author={Arnold J. Sillman and Juliane L. Johnson and Ellis R. Loew},
  journal={The Journal of experimental zoology},
  year={2001},
  volume={290 4},
  pages={
          359-65
        }
}
The photoreceptors of Boa constrictor, a boid snake of the subfamily Boinae, were examined with scanning electron microscopy and microspectrophotometry. The retina of B. constrictor is duplex but highly dominated by rods, cones comprising 11% of the photoreceptor population. The rather tightly packed rods have relatively long outer segments with proximal ends that are somewhat tapered. There are two morphologically distinct, single cones. The most common cone by far has a large inner segment… 
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References

SHOWING 1-10 OF 32 REFERENCES
The photoreceptors and visual pigments in the retina of a boid snake, the ball python (Python regius)
TLDR
The photoreceptors and visual pigments of Python regius were studied using microspectrophotometry and scanning electron microscopy and the results are discussed in relation to the behavior of P. regius.
The photoreceptors and visual pigments of the garter snake (Thamnophis sirtalis): a microspectrophotometric, scanning electron microscopic and immunocytochemical study
TLDR
The small single cones with the 360-nm pigment provide the garter snake with selective sensitivity to light in the near ultraviolet region of the spectrum, which might be important in localization of pheromone trails.
The photoreceptors and visual pigments in the retina of the white sturgeon, Acipenser transmontanus
TLDR
The photoreceptors in the retina of the white sturgeon, Acipenser transmontanus (Chondrostei), were studied by means of scanning electron microscopy, in situ microspectrophotometry, and spectrophotometric analysis of visual pigment extracts, finding evidence for only one rod visual pigment and one cone visual pigment.
Histology and microspectrophotometry of the photoreceptors of a crocodilian, Alligator mississippiensis
TLDR
Examination of the photoreceptors in the retina of Alligator mississippiensis confirms that the alligator retina is duplex with rods dominating but cones present in significant numbers.
The ecology of cone pigments in teleost fishes
Age-related changes in the visual pigments of the white sturgeon (Acipenser transmontanus)
TLDR
Using in situ microspectrophotometry, the spectral absorbance characteristics of the photoreceptors in the retinas of larval, juvenile, and adult white sturgeon (Acipenser transmontanus) were determined and the absence of red-sensitive cones in the larvae, and their presence in older fish was confirmed.
Peak density and distribution of ganglion cells in the retinae of microchiropteran bats: implications for visual acuity.
TLDR
The upper limits of visual acuity were derived on the basis of the assumptions of the sampling theorem of the retinal magnification factors and the number of RGCs per degree of visual angle of several species of microchiropteran (echolocating) bats.
The receptor mosaic of Aotes trivirgatus: Distribution of rods and cones
  • T. Ogden
  • Biology
    The Journal of comparative neurology
  • 1975
TLDR
Variation of densities across the retina was continuous but the ratio of rods to cones remained about 50:1 at all locations.
Is colour vision possible with only rods and blue-sensitive cones?
TLDR
This work investigates the wavelength discrimination of an extremely rare group of individuals, blue-cone monochromats, who have only rods and one class of cones and finds that these individuals can distinguish wavelengths in the twilight region where the rods and blue-sensitive cones are simultaneously active.
...
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