RPE with aggregated and dispersed pigment granules. RPE cells with aggregated pigment granules possess apical processes which appear dark grey in phase contrast micrographs (A). In brightfield micrographs, the processes empty of melanosomes are invisible (B). In contrast, RPE with dispersed pigment granules have processes filled with pigment granules which when viewed with phase contrast optics (C) are refractile and appear bright in some cases (although individual granules cannot be resolved). In brightfield micrographs, the same pigment granules appear brown. Arrowheads indicate the position of distal pigment granules while arrows point to the tips of processes (phase contrast micrographs only). The scale bar represents 20 micrometers.
Johnson and García BMC Cell Biology 2007 8:53 doi:10.1186/1471-2121-8-53