Serial section analysis of coated pits and coated vesicles in soybean protoplasts

Divergent viewpoints have been expressed regarding the existence of free coated vesicles in animal cells; this question has not been carefully addressed with plant tissues. Soybean suspension culture protoplasts were exposed to cationized ferritin (CF) for short times to label coated pits and coated vesicles. A serial section analysis did not reveal deep coated pits with long necks as reported in animal cells. Serial sections clearly demonstrated CF-labelled coated vesicles to be separate organelles and is consistent with the idea that they transfer CF from coated pits to other cytoplasmic organelles during endocytosis.