One feature of eukaryotes is a complex endomembrane system, comprised of the various membranes that are suspended inside the cytoplasm of a eukaryotic cell. These critical membranes create different and structural and functional compartments, called organelles. In eukaryotes the organelles of the endomembrane system include the endoplasmic reticulum, the nuclear membrane, Golgi apparatus, lysosomes, peroxisomes, autophagosomes, and dynamic vesicle traffic.
Theories that address the evolutionary origin of eukaryotic endomembranes have failed to appreciate the outer membrane vesicles (OMVs) that mitochondria, bacteria, and archaea, secrete into their surroundings.
It is thus proposed that a bacterial ancestor to the mitochondria organelle secreted OMVs within the cytosol of its host. Trapped within the cytosol of a host cell, OMVs then naturally fused either with each other or with the host's plasma membrane. The idea continues that as it lived in symbiosis within its host, it then eventually evolved into the eukaryotic endomembrane system. The video narrates and illustrates this theory that this endomembrane system originated from the mitochondria itself.