Proceedings of the Royal Society of London. Series B. Biological Sciences

    The choroidal tapetum of Latimeria chalumnae has been examined by optical, and by transmission and scanning electron microscopy. The retinal epithelium, which contains no pigment, is separated from the tapetum by Bruch’s membrane and the well-developed choriocapillaris. The tapetum itself consists of cells containing stacks of flat hexagonal crystals, shown by paper chromatography to be guanine. The crystals are arranged parallel within each cell; most are also parallel to those in neighbouring cells, though the crystals in some cells make a large angle with the general crystal plane. In the main the crystals lie so that their plane is approximately perpendicular to the optic axis of the eye. Owing to the retinal curvature, the angle of the crystal plane varies with position in the eye. The conditions for reflexion by constructive interference are fulfilled. Few choroidal melanocytes lie among the cells of the tapetum, which is not occlusible.


    This text was harvested from a scanned image of the original document using optical character recognition (OCR) software. As such, it may contain errors. Please contact the Royal Society if you find an error you would like to see corrected. Mathematical notations produced through Infty OCR.