Hepatocytes, like the one shown here, are the most abundant type of cell in the human liver. They play an important role in building proteins; producing bile, a liquid that aids in digesting fats; and chemically processing molecules found normally in the body, like hormones, as well as foreign substances like medicines and alcohol.

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

RNA interference or RNAi is a gene-silencing process in which double-stranded RNAs trigger the destruction of specific RNAs. See 2558 for an unlabeled version of this illustration. Featured in The New Genetics.

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 6534.

An anchor cell (red) pushes through the basement membrane (green) that surrounds it. Some cells are able to push through the tough basement barrier to carry out important tasks--and so can cancer cells, when they spread from one part of the body to another. No one has been able to recreate basement membranes in the lab and they're hard to study in humans, so Duke University researchers turned to the simple worm C. elegans. The researchers identified two molecules that help certain cells orient themselves toward and then punch through the worm's basement membrane. Studying these molecules and the genes that control them could deepen our understanding of cancer spread.

A typical animal cell, sliced open to reveal a cross-section of organelles.

To splice a human gene into a plasmid, scientists take the plasmid out of an E. coli bacterium, cut the plasmid with a restriction enzyme, and splice in human DNA. The resulting hybrid plasmid can be inserted into another E. coli bacterium, where it multiplies along with the bacterium. There, it can produce large quantities of human protein. See image 2565 for a labeled version of this illustration. Featured in The New Genetics.

Hippocampal cells in culture with a neuron in green, showing hundreds of the small protrusions known as dendritic spines. The dendrites of other neurons are labeled in blue, and adjacent glial cells are shown in red.

Meiosis is the process whereby a cell reduces its chromosomes from diploid to haploid in creating eggs or sperm. See image 2546 for a labeled version of this illustration. Featured in The New Genetics.

This illustration of an epoxide-opening cascade promoted by water emulates the proposed biosynthesis of some of the Red Tide toxins.

A spore from the bacterium Bacillus subtilis shows four outer layers that protect the cell from harsh environmental conditions.

These cells get their name from the hairlike structures that extend from them into the fluid-filled tube of the inner ear. When sound reaches the ear, the hairs bend and the cells convert this movement into signals that are relayed to the brain. When we pump up the music in our cars or join tens of thousands of cheering fans at a football stadium, the noise can make the hairs bend so far that they actually break, resulting in long-term hearing loss.

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

Two mouse fibroblasts, one of the most common types of cells in mammalian connective tissue. They play a key role in wound healing and tissue repair. This image was captured using structured illumination microscopy.

A protein called tubulin (green) accumulates in the center of a nucleus (outlined in pink) from an aging cell. Normally, this protein is kept out of the nucleus with the help of gatekeepers known as nuclear pore complexes. But NIGMS-funded researchers found that wear and tear to long-lived components of the complexes eventually lowers the gatekeepers' guard. As a result, cytoplasmic proteins like tubulin gain entry to the nucleus while proteins normally confined to the nucleus seep out. The work suggests that finding ways to stop the leakage could slow the cellular aging process and possibly lead to new therapies for age-related diseases.

If a picture is worth a thousand words, what's a movie worth? For researchers studying cell migration, a "documentary" of fruit fly cells (bright green) traversing an egg chamber could answer longstanding questions about cell movement. See 2315 for video.

These smooth muscle cells were derived from human embryonic stem cells. The nuclei are stained blue, and the proteins of the cytoskeleton are stained green. Image and caption information courtesy of the California Institute for Regenerative Medicine.

The receptor is shown bound to an inverse agonist, doxepin.

The signal is obtained by allowing proteins in human serum to interact with glycan (polysaccharide) arrays. The arrays are shown in replicate so the pattern is clear. Each spot contains a specific type of glycan. Proteins have bound to the spots highlighted in green.

This fruit fly spermatid recycles various molecules, including malformed or damaged proteins. Actin filaments (red) in the cell draw unwanted proteins toward a barrel-shaped structure called the proteasome (green clusters), which degrades the molecules into their basic parts for re-use.

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

Scientists revealed a detailed image of the genetic defect that causes myotonic dystrophy type 2 and used that information to design drug candidates to counteract the disease.

A peripheral nerve cell made from human embryonic stem cell-derived neural crest stem cells. The nucleus is shown in blue, and nerve cell proteins peripherin and beta-tubulin (Tuj1) are shown in green and red, respectively. Related to image 3263.

Many researchers use the mouse (Mus musculus) as a model organism to study mammalian biology. Mice carry out practically all the same life processes as humans and, because of their small size and short generation times, are easily raised in labs. Scientists studying a certain cellular activity or disease can choose from tens of thousands of specially bred strains of mice to select those prone to developing certain tumors, neurological diseases, metabolic disorders, premature aging, or other conditions.

Established in 1953, the Coriell Institute for Medical Research distributes cell lines and DNA samples to researchers around the world. Shown here are Coriell's cryogenic tanks filled with liquid nitrogen and millions of vials of frozen cells.

DNA consists of two long, twisted chains made up of nucleotides. Each nucleotide contains one base, one phosphate molecule, and the sugar molecule deoxyribose. The bases in DNA nucleotides are adenine, thymine, cytosine, and guanine. See image 2542 for a labeled version of this illustration. Featured in The New Genetics.

The fledgling field of X-ray microscopy lets researchers look inside whole cells rapidly frozen to capture their actions at that very moment. Here, a yeast cell buds before dividing into two. Colors show different parts of the cell. Seeing whole cells frozen in time will help scientists observe cells' complex structures and follow how molecules move inside them.

A crystal of bovine milk alpha-lactalbumin protein created for X-ray crystallography, which can reveal detailed, three-dimensional protein structures.

This network map shows molecular interactions (yellow) associated with a congenital condition that causes heart arrhythmias and the targets for drugs that alter these interactions (red and blue).

Taste buds in a mouse tongue epithelium with types I, II, and III taste cells visualized by cell-type-specific fluorescent antibodies. Type II taste bud cells signal sweet, bitter, and umami tastes to the central nervous system by releasing ATP through the voltage-gated ion channel CALHM1. Researchers used a confocal microscope to capture this image, which shows all taste buds in red, type II taste buds in green, and DNA in blue.

More information about this work can be found in the Nature letter "CALHM1 ion channel mediates purinergic neurotransmission of sweet, bitter and umami tastes” by Taruno et. al.

Yeast cells entering mitosis, also known as cell division. The green and magenta dots are two proteins that play important roles in mitosis. They show where the cells will split. This image was captured using wide-field microscopy with deconvolution.

Related to images 6792, 6793, 6794, 6797, 6798, and videos 6795 and 6796.

An Arachnoidiscus diatom with a diameter of 190µm. Diatoms are microscopic algae that have cell walls made of silica, which is the strongest known biological material relative to its density. In Arachnoidiscus, the cell wall is a radially symmetric pillbox-like shell composed of overlapping halves that contain intricate and delicate patterns. Sometimes, Arachnoidiscus is called “a wheel of glass.”

This image was taken with the orientation-independent differential interference contrast microscope.

A crystal of Bence Jones protein created for X-ray crystallography, which can reveal detailed, three-dimensional protein structures.

To become products, reactants must overcome an energy hill. See image 2525 for an unlabeled version of this illustration. Featured in The Chemistry of Health.

Hippocampal neuron from rodent brain with dendrites shown in blue. The hundreds of tiny magenta, green and white dots are the dendritic spines of excitatory synapses.

This image of the human brain uses colors and shapes to show neurological differences between two people. The blurred front portion of the brain, associated with complex thought, varies most between the individuals. The blue ovals mark areas of basic function that vary relatively little. Visualizations like this one are part of a project to map complex and dynamic information about the human brain, including genes, enzymes, disease states, and anatomy. The brain maps represent collaborations between neuroscientists and experts in math, statistics, computer science, bioinformatics, imaging, and nanotechnology.

Sketch of an egg cell.

Myotonic dystrophy is thought to be caused by the binding of a protein called Mbnl1 to abnormal RNA repeats. In these two images of the same muscle precursor cell, the top image shows the location of the Mbnl1 splicing factor (green) and the bottom image shows the location of RNA repeats (red) inside the cell nucleus (blue). The white arrows point to two large foci in the cell nucleus where Mbnl1 is sequestered with RNA.

This map paints a colorful portrait of human genetic variation around the world. Researchers analyzed the DNA of 485 people and tinted the genetic types in different colors to produce one of the most detailed maps of its kind ever made. The map shows that genetic variation decreases with increasing distance from Africa, which supports the idea that humans originated in Africa, spread to the Middle East, then to Asia and Europe, and finally to the Americas. The data also offers a rich resource that scientists could use to pinpoint the genetic basis of diseases prevalent in diverse populations. Featured in the March 19, 2008, issue of Biomedical Beat.

This video shows an instance of abnormal mitosis where chromosomes are late to align. The video demonstrates the spindle checkpoint in action: just one unaligned chromosome can delay anaphase and the completion of mitosis. The cells shown are S3 tissue cultured cells from Xenopus laevis, African clawed frog.

Image showing rhabdomeres (red), the light-sensitive structures in the fruit fly retina, and rhodopsin-4 (blue), a light-sensing molecule.

Cytoplasmic linker protein (CLIP)-170 is a microtubule plus-end-tracking protein that regulates microtubule dynamics and links microtubule ends to different intracellular structures. In this movie, the gene for CLIP-170 has been fused with green fluorescent protein (GFP). When the protein is expressed in cells, the activities can be monitored in real time. Here, you can see CLIP-170 streaming towards the edges of the cell.

Time-lapse video of yeast cells undergoing cell division. Nuclear envelopes are shown in green, and spindle pole bodies, which help pull apart copied genetic information, are shown in magenta. This video was captured using wide-field microscopy with deconvolution.

Related to images 6791, 6792, 6793, 6794, 6797, 6798, and video 6796.

RNA interference or RNAi is a gene-silencing process in which double-stranded RNAs trigger the destruction of specific RNAs. See 2559 for a labeled version of this illustration. Featured in The New Genetics.

Cell-like compartments spontaneously emerge from scrambled frog eggs, with nuclei (blue) from frog sperm. Endoplasmic reticulum (red) and microtubules (green) are also visible. Video created using epifluorescence microscopy.

For more photos of cell-like compartments from frog eggs view: 6584, 6585, 6586, 6591, 6592, and 6593.

For videos of cell-like compartments from frog eggs view: 6588, 6589, and 6590.

A light microscope image shows the chromosomes, stained dark blue, in a dividing cell 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.

The extracellular matrix (ECM) is most prevalent in connective tissues but also is present between the stems (axons) of nerve cells. The axons of nerve cells are surrounded by the ECM encasing myelin-supplying Schwann cells, which insulate the axons to help speed the transmission of electric nerve impulses along the axons.

Confocal image showing high levels of the protein vimentin (white) at the edge zone of a quail embryo. Cell nuclei are labeled green. More specifically, this high-magnification (60X) image shows vimentin immunofluorescence in the edge zone (top of image) and inner zone (bottom of image) of a Stage 4 quail blastoderm. Vimentin expression (white) is shown merged with Sytox nuclear labeling (green) at the edge of the blastoderm. A thick vimentin filament runs circumferentially (parallel to the direction of the edge) that appears to delineate the transition between the edge zone and interior zone. Also shown are dense vimentin clusters or foci, which typically appear to be closely associated with edge cell nuclei. An NIGMS grant to Professor Garcia was used to purchase the confocal microscope that collected this image. Related to image 2808 and video 2809.

This crystal structure shows a conserved hypothetical protein from Mycobacterium tuberculosis. Only 12 other proteins share its sequence homology, and none has a known function. This structure indicates the protein may play a role in metabolic pathways. Featured as one of the August 2007 Protein Structure Initiative Structures of the Month.

By mixing fluorescent dyes like an artist mixes paints, scientists are able to color code individual chromosomes. The technique, abbreviated multicolor-FISH, allows researchers to visualize genetic abnormalities often linked to disease. In this image, "painted" chromosomes from a person with a hereditary disease called Werner Syndrome show where a piece of one chromosome has fused to another (see the gold-tipped maroon chromosome in the center). As reported by molecular biologist Jan Karlseder of the Salk Institute for Biological Studies, such damage is typical among people with this rare syndrome.

This illustration shows, in simplified terms, how the CRISPR-Cas9 system can be used as a gene-editing tool.

For an explanation and overview of the CRISPR-Cas9 system, see the iBiology video, and download the four images of the CRIPSR illustration here.

Histone proteins loop together with double-stranded DNA to form a structure that resembles beads on a string. See image 2560 for an unlabeled version of this illustration. Featured in The New Genetics.