Fernandez H R, Nickel E E
J Cell Biol. 1976 Jun;69(3):721-32. doi: 10.1083/jcb.69.3.721.
The ultrastructure of photoreceptor cells of the crayfish (P. clarkii) has been examined by means of thin sections and freeze-fracturing. The study reveals that in the photoreceptor membranes there are particles associated primarily with the A faces of freeze-fracture preparations which have a mean diameter of 80-84 A and a density of 6,600 per per micrometer2. Treatment of the retina with digitonin (a substance capable of extracting visual photopigments) in Ringer's causes marked disruption of the hexagonal arrangement of the microvilli, breakdown of the microvilli into smaller segments, and gradual removal of the particles. The estimated photopigment concentration in the microvillus is 4,000 per micrometer. It is suggested that the observed particles represent the photopigment in situ.
通过超薄切片和冷冻蚀刻技术，对克氏原螯虾（P. clarkii）光感受器细胞的超微结构进行了研究。研究表明，在光感受器膜中，存在一些主要与冷冻蚀刻标本的A面相关的颗粒，其平均直径为80 - 84埃，每平方微米的密度为6600个。在林格氏液中用洋地黄皂苷（一种能够提取视觉光色素的物质）处理视网膜，会导致微绒毛的六边形排列明显破坏，微绒毛分解成更小的片段，并使颗粒逐渐去除。微绒毛中估计的光色素浓度为每微米4000个。有人认为，观察到的颗粒代表原位光色素。
