Connective tissue is the most abundant and diverse tissue type in the human body, colorfully illustrated here with five different fluorescent proteins.

Image courtesy of Daniela Malide, NIH.

Apoptosis is a form of programmed cell death used to eliminate damaged, infected or unnecessary cells. In this image, serum arrested L-1210 leukemia mouse cells engage in spontaneous apoptosis after nutrient depletion and acid hydrolysis.

Image courtesy of Frank Abernathy.

The genus Drosophila (fruit flies) are among science’s most used animal models, employed by researchers at all stages of the insects’ life. The larval stage depicted covers the first five days after an egg is laid. Three growth phases later, the larva will pupate.

Image courtesy of Chun Han, UC San Francisco.

A false color scanning electron micrograph depicts the microvasculature of a kidney. Red blood cells are colored blue.

Image courtesy of Ruben Sandoval.

The small intestine of a mouse on the 15th day of embryonic development.

Image courtesy of John Hatch, National Heart, Lung and Blood Institute, NIH.

A ring nematode (Mesocriconema sp.). While the nematode C. elegans is a broadly used and useful model organism in research, ring nematodes are plant-parasites that feed on agricultural crops.

Image courtesy of Jonathan Eisenback.

A thin-melt specimen of hippuric acid, a natural metabolite found in human urine. It acts as a biomarker for dietary polyphenol intake (fruits/vegetables) and gut microbiome activity, with levels rising after consuming tea, wine and fruit.

Image courtesy of Brian Johnston.

Confocal microscopy reveals human hair follicles growing from a stem cell-derived organoid (cyan) with nerves (red).

Image courtesy of Karl R. Koehler and Jiyoon Lee.

Depicted in this confocal/deconvolution micrograph are the actin cytoskeleton (cyan) and the endoplasmic reticulum (red) of a mouse brain cancer cell.

Image courtesy of Halli Lindamood and Eric Vitriol.

Darkfield microscopy captures the flowing grace of sperm from Drosophila virilus, a species of fruit fly.

Image courtesy of Earl Nishiguchi.