Anatomy of the mouse retina. Endothelial cell-pericyte ratio and capillary distribution.

A technique is described for preparing whole retinal vascular digests using distilled water and DNase. This produces a more satisfactory preparation of the mouse retinal vascular bed than "trypsin digestion." Nonetheless, the calculation of endothelial cell/pericyte (E/P) ratios based on cell counts from digest preparations has poor reproducibility due to the inability to unequivocally identify at least 25% of the cells in conventionally stained (PAS and hematoxylin) preparations. A more accurate and reproducible means of assessing this ratio uses 1 micron sections of plastic-embedded sections of retina. No effect of age, sex, strain, or area of sampling was found. Capillaries were in three specific bands, centered on the nerve fiber layer, the junction of inner plexiform and inner nuclear layers, and the outer plexiform layers.