The horizontal cells of the cat and rabbit retina have been studied with silver impregnation of whole, flat retinal preparations.
In both mammals, the presence of two different types of horizontal cells have been identified: (a) a symmetrical star-shaped cell in which all the dendrites are of approximately equal length and (b) an asymmetrical horizontal cell. Typical axons were not observed in either cell type.
The ratio of these two types of horizontal cells was different in the two species studied. The proportion of symmetrical to asymmetrical cells was 25:1 and 1:1 in the cat and rabbit, respectively. Another difference between these two mammals was the larger diameter of the dendritic field in the rabbit retina for both symmetrical and asymmetrical cells.
Otherwise the horizontal cells in these two species shared some similarities. The densities of the horizontal cells in the peripheral, peripapillary, and area centralis zones were comparable. Furthermore, the size of the cell body and dendritic field of the horizontal cells in each species varied depending on the retinal region surveyed.
Honrubia FM, Elliott JH. Horizontal Cell of the Mammal Retina. Arch Ophthalmol. 1969;82(1):98-104. doi:10.1001/archopht.1969.00990020100024