To study the detailed morphology of human retinal
ganglion cells, we used intracellular injection of horseradish
peroxidase and Neurobiotin to label over 1000 cells in
an in vitro, wholemount preparation of the human
retina. This study reports on the morphology of 119 wide-field
bistratified and 42 diffuse ganglion cells. Cells were
analyzed quantitatively on the basis of dendritic-field
size, soma size, and the extent of dendritic branching.
Bistratified cells were similar in dendritic-field diameter
(mean ± s.d. = 682 ± 130 μm)
and soma diameter (mean ± s.d. = 18 ±
3.3 μm) but showed a broad distribution in the extent
of dendritic branching (mean ± s.d. branch
point number = 67 ± 32; range = 15–167). Differences
in the extent of branching and in dendritic morphology
and the pattern of branching suggest that the human retina
may contain at least three types of wide-field bistratified
cells. Diffuse ganglion cells comprised a largely homogeneous
group whose dendrites ramified throughout the inner plexiform
layer. The diffuse cells had similar dendritic-field diameters
(mean ± s.d. = 486 ± 113 μm),
soma diameters (mean ± s.d. = 16 ±
2.3 μm), and branch points numbers (mean ± s.d.
= 92 ± 32). The majority had densely branched dendritic
trees and thin, very spiny dendrites with many short, fine,
twig-like thorny processes. Five of the diffuse cells had
much more sparsely branched dendritic trees (<50 branch
points) and less spiny dendrites, suggesting that there
are possibly two types of diffuse ganglion cells in human
retina. Although the presence of a diversity of large bistratified
and diffuse ganglion cells has been observed in a variety
of mammalian retinas, little is known about the number
of cell types, their physiological properties, or their
central projections. Some of the human wide-field bistratified
cells in the present study, however, show morphological
similarities to monkey large bistratified cells that are
known to project to the superior colliculus.
Cell-Subtype-Specific Remodeling of Intrinsically Photosensitive Retinal Ganglion Cells in Streptozotocin-Induced Diabetic Mice
