These images show endosymbiotic bacteria with an emphasis on Rickettsia, which is always mentioned as the alpha-proteobacterial organism that is closest related to mitochondria. This was proposed because these are bacteria that are living inside eukaryotic cells. As I find that mitochondria do not look like bacteria, but more like a eukarytic endomembrane, I am also interested in what these true endosymbiotic bacteria look like under the microscope. The bacteria that I have seen in cell culture are in general distinguishable from for instance yeast or stained mitochondria. As with my other page on mitochondrial morphology, you can judge for yourselves. There are images in which the bacterial localization has the appearance of a reticulum, but most techniques do show the individual bacteria instead of continuous membranes, thereby distinguishing itself from a reticulum.