Who discovered the endoplasmic reticulum?

The endoplasmic reticulum was first observed by Keith R. Porter, with colleagues Albert Claude and Ernest F. Fullam, using electron microscopy in the 1940s.

The endoplasmic reticulum (ER) is a network of membranes inside eukaryotic cells. Early light microscopes could not resolve it. With the rise of electron microscopy, Porter and co-workers described a reticular system in cultured cells and coined the term “endoplasmic reticulum.”

Later, the ER was classified into rough ER, studded with ribosomes for protein synthesis, and smooth ER, which handles lipid metabolism and detoxification. This discovery laid the foundation for cell biology topics like protein folding, vesicle transport, and calcium storage.

ER functions

• Rough ER: protein synthesis and folding
• Smooth ER: lipids, steroids, detox
• Calcium storage and signaling