The visual pigments of rods and cones in the rhesus monkey, Macaca mulatta.

Abstract

SUMMARY1. New microspectrophotometric measurements have been made of the photopigments of individual rods and cones from the retina of the rhesus monkey (Macaca mulatta). The measuring beam was passed transversely through isolated outer segments.2. The transverse absorbance for rods ranged from 0-02 to 0'04 and that for cones from 0.01 to 0'03.3. The mean absorbance spectrum for rods (n = 25) had a peak at 502 + 2*7 nm. A digitonin extract from the same group of eyes gave a Amax. of 499 + 1 nm.4. Of a sample of 82 cones, 40 were 'red' (P565 nm) and 42 were 'green' (P536 nm). The mean absorbance spectrum for the green cones is very similar to the Dartnall nomogram, but that for the red cones is narrower.5. No bleachable, blue-sensitive outer segments were recorded, although structures were found that absorbed at short wave-lengths and were neither photosensitive nor dichroic. 6. If the long wave-length and middle wave-length cone pigments of the rhesus monkey are assumed to be identical to those of man and if additional assumptions are made about the lengths of human outer segments and about prereceptoral absorption, it is possible to derive psychophysical sensitivities that closely resemble the 7rT and i4 mechanisms of W. S. Stiles.

Visual pigments of rods and cones in a human retina.

“…None was recorded in our study of the rhesus monkey (Bowmaker et al 1978), and previous data from three human 'blue' cones give Amax of 460 nm (Marks et al 1964), 450 nm (Brown & Wald, 1964) and 440 nm (Wald & Brown, 1965 Brown. These values are in marked contrast to the present mean transverse absorbance of 0*037.…”

“…In spite of the relatively low signal-noise ratios in primate records (Fig. 1, this paper; see also Bowmaker et al 1978) we believe that these ranges (11 and 15 nm respectively) are significantly greater than one would expect from experimental error. The standard deviation of the ten estimates of Ama.…”

“…Of greater interest than the identity, or otherwise, of the mean Amax values of the various visual pigments in man and rhesus monkey is the evidence, from both this investigation and the previous one (Bowmaker et al 1978), that the Amax values of the 'green' and 'red' cones are spread over an unexpectedly wide range. Only three 'blue' cones were found in the present work (and none in rhesus) so it is not known whether this applies to them also.…”

Visual functions associated with rhesus visual pursuit tracking

“…In recent years, the photopic processes of the rhesus monkey have received considerable attention and generally match the human visual system extremely well. Microspectrophotometric (MSP) measurements of rhesus cone photopigments, measured indiscreetly from foveal and parafoveal retinal regions, compare favorably with psychophysical measurements of cone fundamentals (5). Measurements of rhesus photopic spectral sensitivity have been demonstrated to fit the human photopic functions with small departure in the short wavelength region generally attributed to differences in lens pigmentation (6)(7)(8).…”

“…Adams et al (11) offered the possibility that foveal and parafoveal cones differ in either distribution or in neural interaction. No assumptions were made about differences between foveal and parafoveal cone photopigments, as separation of foveal and parafoveal cones in MSP investigations has not been technically feasible (5).…”