The retina consists of many parallel circuits designed to maximize
the gathering of important information from the environment. Each of
these circuits is comprised of a number of different cell types
combined in modules that tile the retina. To a subterranean animal,
vision is of relatively less importance. Knowledge of how circuits and
their elements are altered in response to the subterranean environment
is useful both in understanding processes of regressive evolution and
in retinal processing itself. We examined common cell types in the
retina of the naked mole-rat, Heterocephalus glaber with
immunocytochemical markers and retrograde staining of ganglion cells
from optic nerve injections. The stains used show that the naked
mole-rat eye has retained multiple ganglion cell types, 1–2 types
of horizontal cell, rod bipolar and multiple types of cone bipolar
cells, and several types of common amacrine cells. However, no labeling
was found with antibodies to the dopamine-synthesizing enzyme, tyrosine
hydroxylase. Although most of the well-characterized mammalian cell
types are present in the regressive mole-rat eye, their structural
organization is considerably less regular than in more sighted mammals.
We found less precision of depth of stratification in the inner
plexiform layer and also less precision in their lateral coverage of
the retina. The results suggest that image formation is not very
important in these animals, but that circuits beyond those required for
circadian entrainment remain in place.