A technique for flat embedding and en face sectioning of the mammalian retina for autoradiography

A method of tissue preparation is described which allows analysis of large areas of the mammalian retina in relatively few 2-5 micrometers sections, and which permits [3H]autoradiography with good resolution and low background. In contrast to standard methods of paraffin embedding and radial sectioning, we have embedded flattened retinas in glycol methacrylate resin and cut sections parallel to the plane of the retinal layers, i.e. en face. As previously shown (Sidman, 1970; Carter-Dawson and LaVail, 1979a, b), methacrylate embedding results in excellent cellular preservation and allows relatively thin sectioning appropriate for [3H]autoradiography and demonstration of cytological detail. Sectioning en face reduces the number of tissue sections required to survey large areas of the retina, and allows reconstruction of the topography of each retinal layer from serial sections. Thus, studies of retinal topography using [3H]autoradiography can now be more easily compared to studies of retinal topography using the whole-mount technique (see Stone, 1981).