The morphology of endosomes in giant HeLa cells

The endosomal compartment of giant HeLa cells was labelled with a transferrin-horse radish peroxidase (HRP) conjugate. Serial thin sections from the leading lamella of a cell are presented; they show that the endosomal compartment contains a tubular system connected to vesicular structures. In addition, small (approximately 50 nm) coated vesicles are seen in the leading lamella.