Collin S P, Collin H B
Scripps Institution of Oceanography, School of Medicine, University of California San Diego, La Jolla.
Brain Behav Evol. 1993;42(2):98-115. doi: 10.1159/000114143.
The cornea of the Florida gar, Lepisosteus platyrhincus (Ginglymodi) was examined at the scanning and transmission electron microscopic levels. In addition, the schematic eye of the garfish was revealed by frozen sectioning of the whole orbit in the horizontal and transverse planes. The lens is spherical, obeys Matthiessen's ratio, and is supported by a dorsal suspensory ligament and a ventral retractor lentis muscle. The cornea, devoid of a spectacle, is comprised anteriorly of an epithelium (eight to ten cells thick) and covered by a layer of flattened cells up to 26 microns in diameter. On the scanning electron microscope, these cells appear to be covered in microplicae and microvilli. Beneath the epithelium lies a granular basement membrane abutting a true Bowman's layer, composed of a random arrangement of collagen fibrils with no keratocytes. The corneal stroma constitutes 54% of the total thickness and contains 55-65 collagen fibril lamellae, oriented perpendicular to neighbouring lamellae. Scattered keratocytes, containing large amounts of mitochondria, lipid droplets and glycogen granules lie in between the perpendicularly oriented lamellae. Posterior to the stroma is a thin and partially broken basement membrane (no true Descemet's membrane exists), adjacent to a monolayered endothelium covered in microvilli. In the periphery, an autochthonous layer is found between the stroma and the endothelium. Stromal pigment granules, enveloped in large nucleated cells, act as a non-occlusible yellow filter in the dorsal cornea. Functional correlations are made and the presence and/or thickness of corneal structures discussed in relation to the evolution of the vertebrate cornea.
对佛罗里达雀鳝（Lepisosteus platyrhincus，雀鳝目）的角膜进行了扫描电子显微镜和透射电子显微镜水平的检查。此外，通过对整个眼眶进行水平和横向平面的冷冻切片，揭示了雀鳝的示意性眼睛。晶状体呈球形，符合马蒂森比例，由背侧悬韧带和腹侧晶状体牵缩肌支撑。角膜没有眼膜，前部由上皮（八到十个细胞厚）组成，并被一层直径达26微米的扁平细胞覆盖。在扫描电子显微镜下，这些细胞似乎覆盖着微褶和微绒毛。上皮下方是一层颗粒状基底膜，与真正的鲍曼层相邻，鲍曼层由随机排列的胶原纤维组成，没有角膜细胞。角膜基质占总厚度的54%，包含55 - 65层胶原纤维板层，与相邻板层垂直排列。散在的角膜细胞含有大量线粒体、脂滴和糖原颗粒，位于垂直排列的板层之间。基质后方是一层薄的且部分断裂的基底膜（不存在真正的德斯密膜），与覆盖着微绒毛的单层内皮相邻。在周边，在基质和内皮之间发现了一层自生层。基质色素颗粒包裹在大的有核细胞中，在背侧角膜中起不可闭塞的黄色滤光器作用。建立了功能相关性，并讨论了角膜结构的存在和/或厚度与脊椎动物角膜进化的关系。
