Anatomy of the retina of the mink (Mustela vison).

The retina of the normal pigmented mink has been studied by light and electron microscopy. This retina resembles the typical vertebrate retinia in its patterns of lamination and synaptic interconnectivity. Rod and cone outer segments and receptor spherule and pedicle endings are found. At least two different types of horizontal cell processes are seen with the electron microscope, suggestive of rabbit A and B types. Ribbon and conventional synapses are found in both plexiform layers; conventional synapses are also present in the inner nuclear layer. Quantitative studies of the inner plexiform layer revealed amacrine:bipolar synapse ratios (3.3:1) similar to those of the cat and monkey. Other quantitative parameters also resembled those previously reported for species with retinas that predominantly contain concentric-type receptive fields.