Where did the endoplasmic reticulum come from?

Found the following on wikipedia. Seems pretty self explanatory: The Golgi, ER, and lysosomes are likely to have evolved as a result of the plasma membrane going through invagination. read more

further support for comes from the fact that the Endoplasmic Reticulum of many living groups are connected directly to the exterior. In red algae for instance the ER is contiguous with the plasmalemma (exterior membrane) . read more

Endoplasmic reticulum or endomembrane evolve along with membrane trafficking components which allows for the transport of vesicle to organelles as well as to the membrane of cell. Proto-eukaryote possess a very simple trafficking system. read more

The endoplasmic reticulum occurs in most types of eukaryotic cells, but is absent from red blood cells and spermatozoa. There are two types of endoplasmic reticulum: rough (granular) and smooth (agranular). The outer face of the rough endoplasmic reticulum is studded with ribosomes that are the sites of protein synthesis. read more