Sillman A J, Govardovskii V I, Röhlich P, Southard J A, Loew E R
Section of Neurobiology, Physiology and Behavior, University of California, Davis 95616, USA.
J Comp Physiol A. 1997 Aug;181(2):89-101. doi: 10.1007/s003590050096.
Scanning electron microscopy, immunocytochemistry, and single cell microspectrophotometry were employed to characterize the photoreceptors and visual pigments in the retina of the garter snake, Thamnophis sirtalis. The photoreceptor population was found to be comprised entirely of cones, of which four distinct types were identified. About 45.5% of the photoreceptors are double cones consisting of a large principal member joined near the outer segment with a much smaller accessory member. About 40% of the photoreceptors are large single cones, and about 14.5% are small single cones forming two subtypes. The outer segments of the large single cones and both the principal and accessory members of the doubles contain the same visual pigment, one with peak absorbance near 554 nm. The small single cones contain either a visual pigment with peak absorbance near 482 nm or one with peak absorbance near 360 nm. Two classes of small single cones could be distinguished also by immunocytochemistry and scanning electron microscopy. 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. This ultraviolet sensitivity might be important in localization of pheromone trails.
利用扫描电子显微镜、免疫细胞化学和单细胞显微分光光度法对束带蛇（Thamnophis sirtalis）视网膜中的光感受器和视觉色素进行了表征。结果发现，光感受器群体完全由视锥细胞组成，其中鉴定出四种不同类型。约45.5%的光感受器是双视锥细胞，由一个大的主细胞和一个小得多的辅助细胞在外段附近相连组成。约40%的光感受器是大的单视锥细胞，约14.5%是形成两个亚型的小单视锥细胞。大的单视锥细胞的外段以及双视锥细胞的主细胞和辅助细胞都含有相同的视觉色素，其峰值吸光度在554nm附近。小单视锥细胞含有峰值吸光度在482nm附近的视觉色素或峰值吸光度在360nm附近的视觉色素。通过免疫细胞化学和扫描电子显微镜也可以区分两类小单视锥细胞。具有360nm色素的小单视锥细胞使束带蛇对光谱中近紫外区域的光具有选择性敏感性。这种紫外敏感性可能在信息素踪迹的定位中很重要。
