The cytoskeleton (green) and DNA (purple) are highlighed in these cells by immunofluorescence.

Detailed three-dimensional reconstruction of a tubular matrix in a thin section of the peripheral endoplasmic reticulum between the plasma membranes of the cell.
The endoplasmic reticulum (ER) is a continuous membrane that extends like a net from the envelope of the nucleus outward to the cell membrane. The ER plays several roles within the cell, such as in protein and lipid synthesis and transport of materials between organelles.
Shown here is a three-dimensional representation of the peripheral ER microtubules. Related to images 5855 and 5856

The cerebellum is the brain's locomotion control center. Found at the base of your brain, the cerebellum is a single layer of tissue with deep folds like an accordion. People with damage to this region of the brain often have difficulty with balance, coordination and fine motor skills.

This image of a mouse cerebellum is part of a collection of such images in different colors and at different levels of magnification from the National Center for Microscopy and Imaging Research (NCMIR). Related to image 5800.

This image shows the uncontrolled growth of cells in squamous cell carcinoma, the second most common form of skin cancer. If caught early, squamous cell carcinoma is usually not life-threatening.

This image was part of the Life: Magnified exhibit that ran from June 3, 2014, to January 21, 2015, at Dulles International Airport.

Yeast cells with nuclei shown in green and contractile rings shown in magenta. Nuclei store DNA, and contractile rings help cells divide. This image was captured using wide-field microscopy with deconvolution.

Related to images 6791, 6793, 6794, 6797, 6798, and videos 6795 and 6796.

Details about the basic biology and chemistry of the ingredients that produce bioluminescence are allowing scientists to harness it as an imaging tool. Credit: Nathan Shaner, Scintillon Institute.

From Biomedical Beat article July 2017: Chasing Fireflies—and Better Cellular Imaging Techniques

Hydra magnipapillata is an invertebrate animal used as a model organism to study developmental questions, for example the formation of the body axis.

Inside the fertilized egg cell of a fruit fly, we see a type of myosin (related to the protein that helps muscles contract) made to glow by attaching a fluorescent protein. After fertilization, the myosin proteins are distributed relatively evenly near the surface of the embryo. The proteins temporarily vanish each time the cells' nuclei--initially buried deep in the cytoplasm--divide. When the multiplying nuclei move to the surface, they shift the myosin, producing darkened holes. The glowing myosin proteins then gather, contract, and start separating the nuclei into their own compartments.

The incredible complexity of a mammalian eye (in this case from a mouse) is captured here. Each color represents a different type of cell. In total, there are nearly 70 different cell types, including the retina's many rings and the peach-colored muscle cells clustered on the left.

This image was part of the Life: Magnified exhibit that ran from June 3, 2014, to January 21, 2015, at Dulles International Airport.

Superresolution microscopy work on endoplasmic reticulum (ER) in the peripheral areas of the cell showing details of the structure and arrangement in a complex web of tubes.
The ER is a continuous membrane that extends like a net from the envelope of the nucleus outward to the cell membrane. The ER plays several roles within the cell, such as in protein and lipid synthesis and transport of materials between organelles. The ER has a flexible structure to allow it to accomplish these tasks by changing shape as conditions in the cell change. Shown here an image created by super-resolution microscopy of the ER in the peripheral areas of the cell showing details of the structure and the arrangements in a complex web of tubes. Related to images 5856 and 5857.

The G switch allows our bodies to respond rapidly to hormones. G proteins act like relay batons to pass messages from circulating hormones into cells. A hormone (red) encounters a receptor (blue) in the membrane of a cell. Next, a G protein (green) becomes activated and makes contact with the receptor to which the hormone is attached. Finally, the G protein passes the hormone's message to the cell by switching on a cell enzyme (purple) that triggers a response. See image 2536 and 2537 for other versions of this image. Featured in Medicines By Design.

The molecules that glow blue in these cultured cells prevent the expression of the mutant proteins that cause Huntington's disease. Biochemist David Corey and others at UT Southwestern Medical Center designed the molecules to specifically target the genetic repeats that code for harmful proteins in people with Huntington's disese. People with Huntington's disease and similar neurodegenerative disorders often have extra copies of a gene segment. Moving from cell cultures to animals will help researchers further explore the potential of their specially crafted molecule to treat brain disorders. In addition to NIGMS, NIH's National Institute of Neurological Disorders and Stroke and National Institute of Biomedical Imaging and Bioengineering also funded this work.

Two models for how material passes through the Golgi apparatus: the vesicular shuttle model and the cisternae maturation model.

During cell division, cells physically divide after separating their genetic material to create two daughter cells that are genetically identical to the parent cell. This process is important so that new cells can grow and develop. In this image, a human fibroblast cell—a type of connective tissue cell that plays a key role in wound healing and tissue repair—is dividing into two daughter cells. A cell protein called actin appears gray, the myosin II (part of the family of motor proteins responsible for muscle contractions) appears green, and DNA appears magenta.

Meiosis is used to make sperm and egg cells. During meiosis, a cell's chromosomes are copied once, but the cell divides twice. During mitosis, the chromosomes are copied once, and the cell divides once. For simplicity, cells are illustrated with only three pairs of chromosomes.

See image 1333 for an unlabeled version of this illustration.

Like a strand of white pearls, DNA wraps around an assembly of special proteins called histones (colored) to form the nucleosome, a structure responsible for regulating genes and condensing DNA strands to fit into the cell's nucleus. Researchers once thought that nucleosomes regulated gene activity through their histone tails (dotted lines), but a 2010 study revealed that the structures' core also plays a role. The finding sheds light on how gene expression is regulated and how abnormal gene regulation can lead to cancer.

Cells move forward with lamellipodia and filopodia supported by networks and bundles of actin filaments. Proper, controlled cell movement is a complex process. Recent research has shown that an actin-polymerizing factor called the Arp2/3 complex is the key component of the actin polymerization engine that drives amoeboid cell motility. ARPC3, a component of the Arp2/3 complex, plays a critical role in actin nucleation. In this photo, the ARPC3+/+ fibroblast cells were fixed and stained with Alexa 546 phalloidin for F-actin (red), Arp2 (green), and DAPI to visualize the nucleus (blue). Arp2, a subunit of the Arp2/3 complex, is localized at the lamellipodia leading edge of ARPC3+/+ fibroblast cells. Related to images 3329, 3330, 3331, 3332, and 3333.

Actin (purple), microtubules (yellow), and nuclei (green) are labeled in these cells by immunofluorescence. This image won first place in the Nikon 2003 Small World photo competition.

Elastin is a fibrous protein in the extracellular matrix (ECM). It is abundant in artery walls like the one shown here. As its name indicates, elastin confers elasticity. Elastin fibers are at least five times stretchier than rubber bands of the same size. Tissues that expand, such as blood vessels and lungs, need to be both strong and elastic, so they contain both collagen (another ECM protein) and elastin. In this photo, the elastin-rich ECM is colored grayish brown and is most visible at the bottom of the photo. The curved red structures near the top of the image are red blood cells.

Neurons (green) and glial cells from isolated dorsal root ganglia express COX-2 (red) after exposure to an inflammatory stimulus (cell nuclei are blue). Lawrence Marnett and colleagues have demonstrated that certain drugs selectively block COX-2 metabolism of endocannabinoids -- naturally occurring analgesic molecules -- in stimulated dorsal root ganglia. Featured in the October 20, 2011 issue of Biomedical Beat.

These images show three stages of cell division in Xenopus XL177 cells, which are derived from tadpole epithelial cells. They are (from top): metaphase, anaphase and telophase. The microtubules are green and the chromosomes are blue. Related to 3443.

Trypanosoma brucei is a single-cell parasite that causes sleeping sickness in humans. Scientists have been studying trypanosomes for some time because of their negative effects on human and also animal health, especially in sub-Saharan Africa. Moreover, because these organisms evolved on a separate path from those of animals and plants more than a billion years ago, researchers study trypanosomes to find out what traits they may harbor that are common to or different from those of other eukaryotes (i.e., those organisms having a nucleus and mitochondria). This image shows the T. brucei cell membrane in red, the DNA in the nucleus and kinetoplast (a structure unique to protozoans, including trypanosomes, which contains mitochondrial DNA) in blue and nuclear pore complexes (which allow molecules to pass into or out of the nucleus) in green. Scientists have found that the trypanosome nuclear pore complex has a unique mechanism by which it attaches to the nuclear envelope. In addition, the trypanosome nuclear pore complex differs from those of other eukaryotes because its components have a near-complete symmetry, and it lacks almost all of the proteins that in other eukaryotes studied so far are required to assemble the pore.

Bioengineers were able to coax bacteria to blink in unison on microfluidic chips. They called each blinking bacterial colony a biopixel. Thousands of fluorescent E. coli bacteria, shown here, make up a biopixel. Related to images 3265 and 3266. From a UC San Diego news release, "Researchers create living 'neon signs' composed of millions of glowing bacteria."

Drugs enter different layers of skin via intramuscular, subcutaneous, or transdermal delivery methods. See image 2531 for an unlabeled version of this illustration. Featured in Medicines By Design.

Using techniques that took 4 years to design, a team of developmental biologists showed that certain proteins can direct the subdivision of fruit fly and chicken nervous system tissue into the regions depicted here in blue, green, and red. Molecules called bone morphogenetic proteins (BMPs) helped form this fruit fly embryo. While scientists knew that BMPs play a major role earlier in embryonic development, they didn't know how the proteins help organize nervous tissue. The findings suggest that BMPs are part of an evolutionarily conserved mechanism for organizing the nervous system. The National Institute of Neurological Disorders and Stroke also supported this work.

Serum albumin (SA) is the most abundant protein in the blood plasma of mammals. SA has a characteristic heart-shape structure and is a highly versatile protein. It helps maintain normal water levels in our tissues and carries almost half of all calcium ions in human blood. SA also transports some hormones, nutrients and metals throughout the bloodstream. Despite being very similar to our own SA, those from other animals can cause some mild allergies in people. Therefore, some scientists study SAs from humans and other mammals to learn more about what subtle structural or other differences cause immune responses in the body.

Related to entries 3725 and 3675.

Moving protein or other molecules to specific cells to treat or examine them has been a major biological challenge. Scientists have now developed a technique for delivering chemicals to individual cells. The approach involves gold nanowires that, for example, can carry tumor-killing proteins. The advance was possible after researchers developed electric tweezers that could manipulate gold nanowires to help deliver drugs to single cells.

This movie shows the manipulation of the nanowires for drug delivery to a single cell. To learn more about this technique, see this post in the Computing Life series.

Cell showing overproduction of the ARTS protein (red). ARTS triggers apoptosis, as shown by the activation of caspase-3 (green) a key tool in the cell's destruction. The nucleus is shown in blue. Image is featured in October 2015 Biomedical Beat blog post Cool Images: A Halloween-Inspired Cell Collection.

RNA incorporated into the CRISPR surveillance complex is positioned to scan across foreign DNA. Cryo-EM density from a 3Å reconstruction is shown as a yellow mesh.

On top, the brain of a sleep-deprived fly glows orange because of Bruchpilot, a communication protein between brain cells. These bright orange brain areas are associated with learning. On the bottom, a well-rested fly shows lower levels of Bruchpilot, which might make the fly ready to learn after a good night's rest.

This image shows a layer of retinal pigment epithelium cells derived from human embryonic stem cells, highlighting the nuclei (red) and cell surfaces (green). This kind of retinal cell is responsible for macular degeneration, the most common cause of blindness. Image and caption information courtesy of the California Institute for Regenerative Medicine. Related to image 3286

Fruit flies are a common model organism for basic medical research.

In the worm C. elegans, double-stranded RNA made in neurons can silence matching genes in a variety of cell types through the transport of RNA between cells. The head region of three worms that were genetically modified to express a fluorescent protein were imaged and the images were color-coded based on depth. The worm on the left lacks neuronal double-stranded RNA and thus every cell is fluorescent. In the middle worm, the expression of the fluorescent protein is silenced by neuronal double-stranded RNA and thus most cells are not fluorescent. The worm on the right lacks an enzyme that amplifies RNA for silencing. Surprisingly, the identities of the cells that depend on this enzyme for gene silencing are unpredictable. As a result, worms of identical genotype are nevertheless random mosaics for how the function of gene silencing is carried out. For more, see journal article and press release. Related to image 6532.

This image shows a cell in two stages of division: prometaphase (top) and metaphase (bottom). To form identical daughter cells, chromosome pairs (blue) separate via the attachment of microtubules made up of tubulin proteins (pink) to specialized structures on centromeres (green).

A Trigonium diatom imaged by a quantitative orientation-independent differential interference contrast (OI-DIC) microscope. Diatoms are single-celled photosynthetic algae with mineralized cell walls that contain silica and provide protection and support. These organisms form an important part of the plankton at the base of the marine and freshwater food chains. The width of this image is 90 μm.

More information about the microscopy that produced this image can be found in the Journal of Microscopy paper “An Orientation-Independent DIC Microscope Allows High Resolution Imaging of Epithelial Cell Migration and Wound Healing in a Cnidarian Model” by Malamy and Shribak.

It has been said that gastrulation is the most important event in a person's life. This part of early embryonic development transforms a simple ball of cells and begins to define cell fate and the body axis. In a study published in Science magazine in March 2012, NIGMS grantee Bob Goldstein and his research group studied how contractions of actomyosin filaments in C. elegans and Drosophila embryos lead to dramatic rearrangements of cell and embryonic structure. This research is described in detail in the following article: "Triggering a Cell Shape Change by Exploiting Preexisting Actomyosin Contractions." In these images, myosin (green) and plasma membrane (red) are highlighted at four timepoints in gastrulation in the roundworm C. elegans. The blue highlights in the top three frames show how cells are internalized, and the site of closure around the involuting cells is marked with an arrow in the last frame. See related video 3334.

The worm Caenorhabditis elegans is a popular laboratory animal because its small size and fairly simple body make it easy to study. Scientists use this small worm to answer many research questions in developmental biology, neurobiology, and genetics. This image, which was taken with transmission electron microscopy (TEM), shows a cross-section through C. elegans, revealing various internal structures.

The image is from a figure in an article published in the journal eLife. There is an annotated version of this graphic at 5760.

This image captures the many layers of nerve cells in the retina. The top layer (green) is made up of cells called photoreceptors that convert light into electrical signals to relay to the brain. The two best-known types of photoreceptor cells are rod- and cone-shaped. Rods help us see under low-light conditions but can't help us distinguish colors. Cones don't function well in the dark but allow us to see vibrant colors in daylight.

This image was part of the Life: Magnified exhibit that ran from June 3, 2014, to January 21, 2015, at Dulles International Airport.

A light microscope image of a cell from the endosperm of an African globe lily (Scadoxus katherinae). This is one frame of a time-lapse sequence that shows cell division in action. The lily is considered a good organism for studying cell division because its chromosomes are much thicker and easier to see than human ones. Staining shows microtubules in red and chromosomes in blue.

Related to images 1010, 1011, 1013, 1014, 1015, 1016, 1017, 1018, 1019, and 1021.

This fluorescent microscope image shows human embryonic stem cells whose nuclei are stained green. Blue staining shows the surrounding supportive feeder cells. Image and caption information courtesy of the California Institute for Regenerative Medicine. See related image 3275.

The nuclei stained green highlight human embryonic stem cells grown under controlled conditions in a laboratory. Blue represents the DNA of surrounding, supportive feeder cells. Image and caption information courtesy of the California Institute for Regenerative Medicine. See related image 3724.

A light microscope image of a cell from the endosperm of an African globe lily (Scadoxus katherinae). This is one frame of a time-lapse sequence that shows cell division in action. The lily is considered a good organism for studying cell division because its chromosomes are much thicker and easier to see than human ones. Staining shows microtubules in red and chromosomes in blue. Here, condensed chromosomes are clearly visible and have lined up in the middle of the dividing cell.

Related to images 1010, 1011, 1012, 1013, 1014, 1015, 1016, 1018, 1019, and 1021.

Pigment cells are cells that give skin its color. In fishes and amphibians, like frogs and salamanders, pigment cells are responsible for the characteristic skin patterns that help these organisms to blend into their surroundings or attract mates. The pigment cells are derived from neural crest cells, which are cells originating from the neural tube in the early embryo. Investigating pigment cell formation and migration in animals helps answer important fundamental questions about the factors that control pigmentation in the skin of animals, including humans. This image shows a pigment cell from zebrafish at high resolution. Related to images 5755, 5756, 5757 and 5758.

Collecting and transporting cellular waste and sorting it into recylable and nonrecylable pieces is a complex business in the cell. One key player in that process is the endosome, which helps collect, sort and transport worn-out or leftover proteins with the help of a protein assembly called the endosomal sorting complexes for transport (or ESCRT for short). These complexes help package proteins marked for breakdown into intralumenal vesicles, which, in turn, are enclosed in multivesicular bodies for transport to the places where the proteins are recycled or dumped. In this image, two multivesicular bodies (with yellow membranes) contain tiny intralumenal vesicles (with a diameter of only 25 nanometers; shown in red) adjacent to the cell's vacuole (in orange).

Scientists working with baker's yeast (Saccharomyces cerevisiae) study the budding inward of the limiting membrane (green lines on top of the yellow lines) into the intralumenal vesicles. This tomogram was shot with a Tecnai F-20 high-energy electron microscope, at 29,000x magnification, with a 0.7-nm pixel, ~4-nm resolution.

To learn more about endosomes, see the Biomedical Beat blog post The Cell’s Mailroom. Related to a microscopy photograph 5768 that was used to generate this illustration and a zoomed-in version 5767 of this illustration.

Learn about basic science, sometimes called “pure” or “fundamental” science, and how it contributes to the development of medical treatments. Discover more resources from NIGMS’ Pathways collaboration with Scholastic. View the video on YouTube for closed captioning.

The largest human cell (by volume) is the egg. Human eggs are 150 micrometers in diameter and you can just barely see one with a naked eye. In comparison, consider the eggs of chickens...or ostriches!

To develop a system for studying cell motility in unnatrual conditions -- a microscope slide instead of the body -- Tom Roberts and Katsuya Shimabukuro at Florida State University disassembled and reconstituted the motility parts used by worm sperm cells.

Human cells with the gene that codes for the protein FIT2 deleted. After an experimental intervention, they are expressing a nonfunctional version of FIT2, shown in green. The lack of functional FIT2 affected the structure of the endoplasmic reticulum (ER), and the nonfunctional protein clustered in ER membrane aggregates, seen as large bright-green spots. Lipid droplets are shown in red, and the nucleus is visible in gray. This image was captured using a confocal microscope. Related to image 6773.

Using an electrode, researchers apply an electrical pulse onto a piece of muscle tissue affected by Huntington's disease.

Bacterial biofilms are tightly knit communities of bacterial cells growing on, for example, solid surfaces, such as in water pipes or on teeth. Here, cells of the bacterium Bacillus subtilis have formed a biofilm in a laboratory culture. Researchers have discovered that the bacterial cells in a biofilm communicate with each other through electrical signals via specialized potassium ion channels to share resources, such as nutrients, with each other. This insight may help scientists to improve sanitation systems to prevent biofilms, which often resist common treatments, from forming and to develop better medicines to combat bacterial infections. See the Biomedical Beat blog post Bacterial Biofilms: A Charged Environment for more information.