This study provides a quantitative analysis of the major cell populations in the C57 mouse retina. Rod and cone photoreceptors were counted using differential interference contrast microscopy, while horizontal, bipolar, amacrine, and Müller cells were identified through serial section electron microscopy. Ganglion cells and displaced amacrine cells were counted by subtracting the number of axons in the optic nerve from the total neurons in the ganglion cell layer. The results show that the mouse retina is rod-dominated, with rods outnumbering cones by a ratio of approximately 35:1. The inner nuclear layer cells are small and distributed at 3.1% horizontal cells, 41% bipolar cells, 16% Müller cells, and 39% amacrine cells. The ganglion cell layer contains an average of 8200 cells/mm², with 41% being ganglion cells. The study also found that the fractions of bipolar and amacrine cells in the mouse retina are similar to those in the rabbit and monkey, contradicting the belief that lower mammals' retinas are more complex due to a higher proportion of amacrine cells. The findings provide a reference for future genetic studies on the retina and clarify the comparative structure of mammalian visual systems.This study provides a quantitative analysis of the major cell populations in the C57 mouse retina. Rod and cone photoreceptors were counted using differential interference contrast microscopy, while horizontal, bipolar, amacrine, and Müller cells were identified through serial section electron microscopy. Ganglion cells and displaced amacrine cells were counted by subtracting the number of axons in the optic nerve from the total neurons in the ganglion cell layer. The results show that the mouse retina is rod-dominated, with rods outnumbering cones by a ratio of approximately 35:1. The inner nuclear layer cells are small and distributed at 3.1% horizontal cells, 41% bipolar cells, 16% Müller cells, and 39% amacrine cells. The ganglion cell layer contains an average of 8200 cells/mm², with 41% being ganglion cells. The study also found that the fractions of bipolar and amacrine cells in the mouse retina are similar to those in the rabbit and monkey, contradicting the belief that lower mammals' retinas are more complex due to a higher proportion of amacrine cells. The findings provide a reference for future genetic studies on the retina and clarify the comparative structure of mammalian visual systems.