1982 Volume 58 Issue 4-6 Pages 289-303
Cationized ferritin (CF) was used as a visual probe for surface anionic sites in the thyroid follicle epithelial cells. The rat thyroid glands were dissociated by enzyme digestion. The sheets of follicle cells maintained their structural polarity. When labeled after aldehyde fixation, CF was uniformly distributed over the entire cell surface in a thin layer. No regional difference in CF binding pattern was seen. When living cells were Iabeled at 0-4°C, CF was randomly scattered in a dispersed fashion on the apical surface, while the baso-lateral surface was heavily coated with a continuous thick layer of CF. When living cells were incubated with CF at 37°C, a small number of CF were found in clusters along the microvilli on the apical surface, while CF remained continuously and evenly on the baso-lateral surface similar to that of the cells labeled at 0-4°C. These regional differences in binding pattern of CF suggest differences in the properties between the apical and the baso-lateral membranes. It may contribute to maintain the structural and functional polarity in thyroid follicle epithelial cells.
