Salmonella can survive weeks outside the body. This is actually a transmission electron microscopy image, which is similar to an SEM in that it uses electron beams but instead of scanning the surface of an object the beam passes through thin sections of a specimen.
Scanning electron micrograph of light receptors (rods and cones) in the eye. Rods are long nerve cells which respond to dim light, enabling images to be detected. Cones are shorter cells which detect color. Rods and cones pass visual signals through the optic nerve to the brain. Credit: RALPH C. EAGLE, JR. /SCIENCE PHOTO LIBRARY
At a synapse an electrical signal is transmitted from one cell to the next in only one direction. The nerve cells are green, with the pre-synaptic cell at lower right and the post-synaptic cell at upper left. Mitochondria are purple. Neurotransmitter chemicals from vesicles are red. Magnification 50,000x. Image by Science photo library.