The interior of a whole and unmodified biological object - the zymogen granule - viewed with a high-resolution X-ray microscope

We report the ability of focused soft X-rays to visualize at spatial resolution well beyond that of the optical microscope (< 100 nm) the interior of a small, whole biological object without fixation, staining dehydration or sectioning. Quantitative estimation of its protein content with unique femtogram sensitivity is also reported. The present results represent a significant step towards the goals of natural imaging and chemical mapping of biological structures with soft X-rays. © 1989.