Get ready. These are the best. These are hand sections cut by myself and Paige Prentice, then stained with toluidine blue in the Pittermann Lab at UCSC. We stained the sections for contrast, because we were doing our best to find undamaged sieve elements in thick sections.
Even more incredible are the electron microscope photos (in black and white) taken with Michael Knoblauch at the Francheschi Center for Microscopy and Imaging at WSU. These micrographs are so incredibly tiny that you can see actual chloroplasts and cell wall microfibrils in the kelp cells. To generate the Transmission Electron Microscope images, we had to use an ultramicrotome to cut slices of kelp tissue that were only 100 nanometers thick. This incredibly thin section allows the electron beam (which is used instead of light) to pass through the “empty” cell lumens and get absorbed/backscattered by cell walls and structures.
We measured all of these cells for my work on the scaling and allometry of sieve elements, and the entire carbohydrate transport network, in several species of brown algae (Phaeophyceae) within the family Laminariales (the “true kelps”).