Myelinated axons are depicted in a rat spinal root. Myelin is a type of fat that forms an insulating sheath around the axon to protect it from losing electrical current needed to transmit signals. Axoplasm inside the axon is shown in pink.

Image courtesy of the National Center for Microscopy and Imaging Research at UC San Diego.

In the world of animal models, naked mole rats are supermodels despite their novel appearance. They are extremely long-lived, sometimes more than 30 years. They rarely get cancer. And they can survive up to 18 minutes without oxygen.

Hearing begins in the cochlea, where hair cells (red) detect and amplify sound vibrations and relay the information to the brain via auditory nerve cells (green).

Image courtesy of Sonja Pyott, University of North Carolina.

A confocal micrograph depicts tongue epithelial cells adjoined by several bacterial species to form a complex biofilm on the tongue’s surface. The oral cavity has the second largest and most diverse microbiota after the gut.

Image courtesy of Tagide deCarvalho, University of Maryland, Baltimore County.

In this micrograph of a liver lesion from a mouse infected with Chromobacterium violaceum, some cells are dying (red) while other healthy cells (blue) are activating a protein (green) to fight the bacteria.

Image courtesy of Edward Miao at Duke University and Vivien Maltez at University of North Carolina at Chapel Hill.

This is an organoid comprised of human pluripotent colon cells with the metabolic enzyme MTHFD2 stained in red. Scientists have discovered that metabolic enzymes, involved in a cell’s energy production, also perform jobs like orchestrating cell division.

Image courtesy of Natalia Pardo Lorente at Centro de Regulación Genómica in Spain.

These crinkly blooms are groups of bacteriophages, viruses that infect bacteria. After researchers treated phages so they could be viewed under a microscope, the viruses spontaneously formed into these structures, which are just 2/10ths of millimeter wide. By comparison, 1 millimeter is comparable to a sharp pencil point.

Image courtesy of McMaster University, Canada.

A spider is coated in gold to prepare it as a specimen for scanning electron microscopy. Gold is used because of its high electrical conductivity, which enables the electron beam to interact with a specimen more effectively.

Image courtesy of Steve Gschmeissner.

A colorized scanning electron micrograph reveals in fine detail human sperm traveling through a fallopian tube. Ciliated cells (purple with hairlike extensions) help move eggs from the ovary to the uterus and regulate flow of fluid. Secretory cells (green) produce a nutrient-rich fluid that bathes sperm and egg.

Image courtesy of Steve Gschmeissner.

A differential interference contrast image of an amoeba magnified 60 times. Amoebas are a type of cell or unicellular organism with the ability to alter their shape, primarily by extending and retracting pseudopods or “false feet.”

Image courtesy of Håkan Kvarnström, Stockholm, Sweden and Nikon.