Research overview: ultrastructure of the feline tapetal layer

Microscopy has revealed how the feline tapetum is built from highly ordered cells packed with reflective material, arranged in layers behind the retina between the photoreceptors and the choroid. This overview surveys ultrastructural descriptions of the tapetum cellulosum, including the regular stacking of crystal-bearing cells that functions as a multilayer reflector. The geometry of these layers determines which wavelengths are reflected most efficiently, tuning the tapetum to the retina's sensitivity. The survey connects this fine structure to the optical performance and eyeshine color described in behavioral and reflectance studies. It also notes how the tapetum is positioned to intercept light that has already passed the photoreceptors. Detailed ultrastructure matters because it shows the tapetum is a precisely organized optical device, and it provides the physical basis for explaining the layer's reflective behavior and its role in night vision.