Collin S P, Collin H B
Department of Physiology and Pharmacology, University of Queensland, St. Lucia, Australia.
Exp Biol. 1988;47(4):209-18.
The sandlance, Limnichthyes fasciatus (Creeiidae), is a small teleost (30 mm in length), which lives beneath the sand. It has minute dorsally placed eyes (1.04 mm in diameter), which move independently of one another. The structure of the retina and lens was examined by both light and electron microscopy. A deep convexiclivate fovea lies on the visual axis of the eye, and regional increases in photoreceptor and ganglion cell densities occur within the area surrounding the foveal depression. The sandlance possesses a pure cone fovea, with a regular square mosaic of a single cone bordered by four equal double cones distributed over most of the retina. Rods are rare and are distinguishable from cones on ultrastructural morphology. A pigmented choriocapillaris extends behind the retina, closely apposing the retinal pigment epithelial cell layer and Bruch's membrane. Surrounding the optic nerve, and adjacent to the choriocapillaris, is a vascularised, horseshoe-shaped choroidal gland, or rete mirabile. A small system of vitreal blood vessels from the hyaloid artery near the optic nerve, supplies the large number of ganglion cells, arranged in up to five sub-laminae, within the ganglion cell layer. The retina is jacketed by an uveal argentea within the sclera. This argentea contains plates of guanine crystals, oriented with their flat surfaces approximately perpendicular to the incident light path, and discrete bundles of melanosomes apposing the sclera. A non-spherical lens, previously described only in deep-sea teleosts, was found, and its refractive properties are discussed in relation to the deep pit fovea.
玉筋鱼，Limnichthyes fasciatus（玉筋鱼科），是一种小型硬骨鱼（体长30毫米），生活在沙层之下。它有微小的位于背部的眼睛（直径1.04毫米），两只眼睛可彼此独立移动。通过光学显微镜和电子显微镜检查了视网膜和晶状体的结构。在眼睛的视轴上有一个深的凸面中央凹，在中央凹凹陷周围的区域，光感受器和神经节细胞密度增加。玉筋鱼拥有一个纯锥体细胞中央凹，在视网膜的大部分区域，单个视锥细胞有规则的方形镶嵌排列，由四个相等的双视锥细胞围绕。视杆细胞很少见，可通过超微结构形态与视锥细胞区分开来。色素性脉络膜毛细血管延伸到视网膜后方，紧密贴附于视网膜色素上皮细胞层和布鲁赫膜。在视神经周围并与脉络膜毛细血管相邻的是一个血管化的马蹄形脉络膜腺，即神奇网。来自视神经附近玻璃样动脉的一个小的玻璃体血管系统，为神经节细胞层中排列多达五个亚层的大量神经节细胞提供血液供应。视网膜在巩膜内被一层银色葡萄膜包裹。这层银色葡萄膜包含鸟嘌呤晶体板，其平坦表面大致垂直于入射光路排列，以及紧贴巩膜的离散黑素体束。发现了一种以前仅在深海硬骨鱼中描述过的非球形晶状体，并结合深凹中央凹讨论了其屈光特性。
