[Comparative morphologic features of the retinas of insectivores and primates]

By means of scanning electron microscopy and by neurohistological methods with subsequent quantitative treatment of the data, it is demonstrated that the retina of the hedgehog differs from that of the green monkey. In the former, the density of photoreceptors convergence is higher, that corresponds to the night mode of life of the hedgehog Monotony in the cells of all the layers, lack of photoreceptor differentiation according to the form of their external segments corresponds to general low level in the organization of the hedgehog nervous system. The retina of the hedgehog possessing the above mentioned structural peculiarities can be considered as a model reflecting the organization in the peripheral portion of the optic analyzer of the original forms in Mammalia placentalia.