A colorized scanning electron micrograph of a human proximal tubule. These tubules make up a significant portion of the kidneys and carry out diverse regulatory and endocrine functions. For example, under normal circumstances more than two-thirds of filtered salt and water is reabsorbed in proximal tubules.

Image courtesy of David Gergory and Debbie Marshall, Wellcome Collection.

A polarized light micrograph captures the colorful character of caffeine crystals. Caffeine is a central nervous system stimulant that works by blocking the binding of adenosine to its receptor, which enhances release of the neurotransmitter acetylcholine, which in the brain supports cognitive functions and boosts muscle activity in the body.

Image courtesy of Stefan Eberhard, University of Georgia and Nikon Small World.

A false color scanning electron micrograph depicts an axon terminal broken open to reveal internal neurotransmitter vesicles. These vesicles are released at neural synapses to carry electrical nerve impulses from one neuron to another.

Image courtesy of Tina Carvalho/NIH-NIGMS.

The distribution of metabolites (small molecules produced while chemical reactions take place in a cell to provide energy) in cells in a mouse kidney. Three small molecules (the amino acids aspartate and glutamine and the antioxidant glutathione) were visualized using a technique called computational molecular phenotyping (CMP). Grayscale light micrographs were taken of silvered antibodies against aspartate, glutamine and glutathione and these were then digitally converted into red, blue and green respectively.

Image courtesy of Jefferson R. Brown, Robert E. Marc, Bryan W. Jones, Glen Prusky and Nazia Alam.

Fluorescence immunohistochemistry and confocal microscopy were used to create this array of normal and cancerous human tissue samples. Human prostate, colon, kidney, intestine and breast tissue sections were stained for the presence of protein biomarkers to improve cancer diagnosis and prognosis.

Image courtesy of Aamir Ahmed, Jane Pendjiky and Michael Millar.

A polarized light micrograph of a section of cat skin showing hairs, whiskers and their blood supply, created from a vintage prepared slide dating before 1900.

Blood vessels were injected with dye (carmine; black) before fixing and sectioning the tissue in order to visualize the capillaries in the tissue. This was a newly developed technique at that time. The capillary bed seen here supplies the hairs and whisker. The fine hairs, thicker whisker, blood vessels and underlying muscle are all visible.

Image courtesy of David Linstead, Wellcome Images.

A large-scale, high-resolution montage of the entire surface of a mouse retina using antibody labeling and laser scanning confocal imaging. Complete networks of both astrocytes and blood vessels on the retinal surface are shown: astrocyte cell bodies are red, the star-shaped extensions from the astrocyte cell bodies are green and blood vessels are blue.

Image courtesy of Gabriel Luna, UC Santa Barbara.

Researchers doing behavioral experiments with honeybees sometimes use paint or enamel to give individual bees distinguishing marks. The elaborate social structure and impressive learning and navigation abilities of bees make them good models for behavioral and neurobiological research.

Image courtesy of Claudia Lutz and Charley Nye, University of Illinois at Urbana-Champaign.

Axolotls are a type of salamander often studied for their extensive regenerative abilities. They can regrow tails, limbs, spinal cords, brains and more. This axolotl has been genetically modified so that its developing nervous system glows purple and its Schwann cell nuclei appear light blue to help illuminate the role of the peripheral nervous system during limb regeneration.

Image courtesy of Marko Pende, Hannover Medical School.

Actin is an essential protein in a cell’s skeletal structure, forming a sense network of thin supporting filaments. In this image, using a technique called stochastic optical reconstruction microscopy, dyed actin strands crisscross a cell.

Image courtesy of Xiaowei Zhuang, HHMI, Harvard University, and Nature Publishing Group.