Human embryonic stem cell colony, using confocal and image stitching microscopy.

Image courtesy of Nilay Taneja, Vanderbilt University.

A knotted strand of human hair. Typically, a single strand of human hair is between 0.03mm and 0.06 mm in thickness, comparable to the width of a human skin cell and thinner than a fruit fly’s eye.

Image courtesy of Robert Vierthaler, Pfarrwerfen, Salzburg, Austria.

The cerebellum of a rat brain, with astrocytes and neurons, captured using confocal microscopy with immunohistological staining.

Image courtesy of Barbara Orsolits, Semmelweis University, Budapest, Hungary.

A colorized scanning electron micrograph of mouse fat cells (red) surrounded by a network of blood vessels (green).

Image courtesy of Daniel Malide, National Heart, Lung and Blood Institute, NIH.

Hepatocytes or liver cells are the most abundant cell type in the human liver, and play multiple roles, including building proteins, producing bile to aid digestion of fats and chemically processing molecules found normally in the body, like hormones, as well as foreign substances like medicines and alcohol.

Image courtesy of Donna Beer Stolz, University of Pittsburgh.

A confocal micrograph of Drosophila (fruit fly) ovirioles. In female insects, ovirioles are tubes in which eggs cells form at one end and complete development as they reach the other end of the tube. Scientists use insect ovarioles to study basic processes that help insects, including those that cause disease, reproduce quickly.

Image courtesy of National Institutes of Health.

The face of a 6-day-old zebrafish larva, one of science’s preferred animal models. What look like eyes will develop into nostrils and the bulges on either side will become eyes.

Image courtesy of Oscar Ruiz and George Eisenhoffer, University of Texas MD Anderson Cancer Center.

Micrograph of mouse keratinocytes, a major cell type of the epidermis or outermost layer of skin.

Image courtesy of Nancy Kedersha, ImmunoGen, Inc.

Darkfield micrograph of human scalp section.

Image courtesy of Anita L. Tellier, Rochester Institute of Technology.

A confocal micrograph of blood vessel networks in the intestine of an adult mouse.

Image courtesy of Satu Paavonsalo and Sinem Karaman, University of Helsinki.