Mini-review Discovery of a new cellular structure—the porosome: elucidation of the molecular mechanism of secretion

Invention of the light microscope some 300 years ago allowed discovery of the unit of life, the cell. Up until the early 1940s, the light microscope, so efficient in the 19th century, reached the limits of its resolving power, of some 200 nanometer in lateral resolution and much less in its depth resolution. With the invention of the electron microscope and its use in biological research, a new era dawned for cell biology, when major subcellular organelles, and their organization and function, were elucidated. Pioneering cell biologists—George E. Palade, Keith Porter, and Albert Claude—made stellar contributions during this period. With a lateral resolving power of nearer a nanometer, the electron microscope matured into the ultimate imaging tool in the study of the cell. Unlike the light microscope, the electron micro