Development of the outer plexiform layer in albino rats

The development of the outer plexiform layer (OPL) at the posterior pole was studied in albino rats, ages 1 to 18 days. Light microscopic observations were consistent with previous reports that within the first postnatal week neuro-epithelial cells migrate into outer and inner nuclear layers with formation of the intervening OPL. The relation of neural and glial cells was consistent with the suggestion of others that guidance by glial cells influences the radial organization of the developing neural retina. The new observations presented in this paper raise the possibility that the horizontal orientation of neural processes in the outer plexiform layer depends upon guidance of glial cells.