The morphology of the cat tapetum lucidum

Tapetum lucidum is a comparatively neglected structure found in many species used in vision research. Fundus photography and light and electron microscopy were used in this study to provide more information about the macro- and microstructure of this reflectant layer. In the cat, the tapetum is a lamellar choroidal structure formed by (in cross-section) rectangular cells containing groups of parallel crystal rods. Within each cell these groups of rods lie at various angles to each other but in a plane approximately parallel to the retina. The basal lamina (Bruch's membrane) is poorly developed or absent, and the retinal pigment epithelium contains relatively few pigment granules. It is thought that the function of tapetum lucidum is to reflect light that has not stimulated the retina back into the receptor cells for a second chance of absorption by the visual pigments, thus enhancing night vision.