Possible roles of microtubules and actin filaments in retinal pigmented epithelium

To investigate the roles of actin filaments and microtubules in the dramatic light-induced pigment migration in pigmented epithelia of crepuscular fishes, light and dark adapted retinas from the grey snapper were examined by electron microscopy.

Abstract

The distribution of cytoplasmic filaments and microtubules in retinal pigmented epithelial cells has been examined in an attempt to elucidate their roles in motile activities of these cells. Pigmented epithelia of normal and dystrophic rats were compared with special reference to possible roles of filaments and microtubules in phagocytosis of effete photoreceptor outer segments. In both normal and dystrophic rats, the plasma membranes of the apical projections of the pigmented epithelial cells are lined on their cytoplasmic face with parallel rows of axially oriented filaments. Microtubules are absent from the apical projections but numerous in the nearby apical cytoplasm. To investigate the roles of actin filaments and microtubules in the dramatic light-induced pigment migration in pigmented epithelia of crepuscular fishes, light and dark adapted retinas from the grey snapper (lutjanus griseus) were examined by electron microscopy. The long apical projections of this pigmented epithelium contain both actin filaments (as ascertained by myosin subfragment-1 binding) and numerous axial microtubules. Possible roles of actin filaments and microtubules in phagocytosis and in pigment migration are discussed.