Packer O S, Williams D R, Bensinger D G
Center for Visual Science, University of Rochester, New York 14627, USA.
J Neurosci. 1996 Apr 1;16(7):2251-60. doi: 10.1523/JNEUROSCI.16-07-02251.1996.
We introduce a new technique for classifying many photoreceptors simultaneously in fresh, excised primate retina on the basis of their absorptance spectra. Primate retina is removed from the pigment epithelium and illuminated under a microscope from the same direction as in the intact eye. To facilitate the guiding of light into the receptor outer segments, the optical axes of the photoreceptors are oriented parallel to the optical axis of the microscope. Photoreceptor outer-segment tips are imaged on a charge-coupled device array, which provides radiometric measurements of the light passing through each photoreceptor. These images are acquired sequentially at three wavelengths chosen to maximize the absorptance differences among the three cone photopigments. After the photopigment is bleached, a second set of three images is acquired. The ratios of the images before and after bleaching at each wavelength are photopigment transmittance maps of the retina. These are combined into a single trichromatic image showing the distribution of photopigment if the retina could be viewed directly in white light without bleaching. We have found patches of receptors in peripheral macaque retina where the measured absorptance at the wavelength of maximum absorptance is consistent with the predicted axial absorptance of th photopigment. The cones in these patches cluster into two groups corresponding to the middle wavelength-sensitive (n = 53, mean absorptance = 0.28) and the long wavelength-sensitive (n = 63, mean absorptance = 0.30) cones. The mean absorptances of 273 macaque and 183 human rods were 0.51 and 0.41, respectively.
我们介绍了一种新技术，可基于吸收光谱同时对新鲜切除的灵长类动物视网膜中的许多光感受器进行分类。将灵长类动物视网膜从色素上皮移除，并在显微镜下从与完整眼睛相同的方向进行照明。为便于将光导入感受器外段，使光感受器的光轴与显微镜的光轴平行。光感受器外段尖端成像于电荷耦合器件阵列上，该阵列可提供穿过每个光感受器的光的辐射测量。这些图像在三个选定波长下依次采集，以最大化三种视锥光色素之间的吸收差异。在光色素漂白后，采集第二组三张图像。每个波长下漂白前后图像的比率即为视网膜的光色素透射率图。如果视网膜能在不漂白的情况下直接用白光观察，这些图可组合成一张显示光色素分布的单一三色图像。我们在猕猴周边视网膜中发现了一些感受器斑块，在这些斑块中，最大吸收波长处测得的吸收率与光色素预测的轴向吸收率一致。这些斑块中的视锥细胞聚为两组，分别对应中波长敏感视锥细胞（n = 53，平均吸收率 = 0.28）和长波长敏感视锥细胞（n = 63，平均吸收率 = 0.30）。273个猕猴视杆细胞和183个人类视杆细胞的平均吸收率分别为0.51和0.41。
