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

Zinc is required for the function of more than 300 enzymes, including those that help regulate gene expression, in various organisms including humans. Researchers study how plants acquire, sequester and distribute zinc to find ways to increase the zinc content of crops to improve human health. Using synchrotron X-ray fluorescence technology, they created this heat map of zinc levels in an Arabidopsis thaliana plant leaf. This image is a winner of the 2015 FASEB Bioart contest and was featured in the NIH Director's blog.

Body organs such as the liver and kidneys process chemicals and toxins. These "target" organs are susceptible to damage caused by these substances. See image 2497 for a labeled version of this illustration.

Cells function within organs and tissues, such as the lungs, heart, intestines, and kidney.

Learn how research organisms, such as fruit flies and mice, can help us understand and treat human diseases. Discover more resources from NIGMS’ Pathways collaboration with Scholastic. View the video on YouTube for closed captioning.

Many disease-causing microbes manipulate their host’s metabolism and cells for their own ends. Microsporidia—which are parasites closely related to fungi—infect and multiply inside animal cells, and take the rearranging of cells’ interiors to a new level. They reprogram animal cells such that the cells start to fuse, causing them to form long, continuous tubes. As shown in this image of the roundworm Caenorhabditis elegans, microsporidia (shown in magenta) have invaded the worm’s gut cells (shown in yellow; the cells’ nuclei are shown in blue) and have instructed the cells to merge. The cell fusion enables the microsporidia to thrive and propagate in the expanded space. Scientists study microsporidia in worms to gain more insight into how these parasites manipulate their host cells. This knowledge might help researchers devise strategies to prevent or treat infections with microsporidia. For more on the research into microsporidia, see this news release from the University of California San Diego. Related to images 5778 and 5779.

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, a multivesicular body (the round structure slightly to the right of center) contain tiny intralumenal vesicles (with a diameter of only 25 nanometers; the round specks inside the larger round structure) adjacent to the cell's vacuole (below the multivesicular body, shown in darker and more uniform gray).

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 color-enhanced version 5767 and image 5769.

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.

The green in this image highlights a protein called TonB, which is produced by many gram-negative bacteria, including those that cause typhoid fever, meningitis and dysentery. TonB lets bacteria take up iron from the host's body, which they need to survive. More information about the research behind this image can be found in a Biomedical Beat Blog posting from August 2013.

Neutrophil-like cells (blue) in a microfluidic chip preferentially migrating toward LTB4 over fMLP. A neutrophil is a type of white blood cell that is part of the immune system and helps the body fight infection. Both LTB4 and fMLP are molecules involved in immune response. Microfluidic chips are small devices containing microscopic channels, and they are used in a range of applications, from basic research on cells to pathogen detection. The scale bar in this video is 500μm.

Cells walk along body surfaces via tiny "feet," called focal adhesions, that connect with the extracellular matrix. See image 2503 for a labeled version of this illustration.

Lysosomes (yellow) and detyrosinated microtubules (light blue). Lysosomes are bubblelike organelles that take in molecules and use enzymes to break them down. Microtubules are strong, hollow fibers that provide structural support to cells. The researchers who took this image found that in epithelial cells, detyrosinated microtubules are a small subset of fibers, and they concentrate lysosomes around themselves. This image was captured using Stochastic Optical Reconstruction Microscopy (STORM).

Related to images 6890, 6891, and 6892.

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.

These developing mouse nerve cells have a nucleus (yellow) surrounded by a cell body, with long extensions called axons and thin branching structures called dendrites. Electrical signals travel from the axon of one cell to the dendrites of another.

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

Illustration of a sperm, the male reproductive cell.

A fruit fly ovary, shown here, contains as many as 20 eggs. Fruit flies are not merely tiny insects that buzz around overripe fruit—they are a venerable scientific tool. Research on the flies has shed light on many aspects of human biology, including biological rhythms, learning, memory, and neurodegenerative diseases. Another reason fruit flies are so useful in a lab (and so successful in fruit bowls) is that they reproduce rapidly. About three generations can be studied in a single month.

Related to image 3656. This image was part of the Life: Magnified exhibit that ran from June 3, 2014, to January 21, 2015, at Dulles International Airport.

What looks a little like distant planets with some mysterious surface features are actually assemblies of proteins normally found in the cell's nucleolus, a small but very important protein complex located in the cell's nucleus. It forms on the chromosomes at the location where the genes for the RNAs are that make up the structure of the ribosome, the indispensable cellular machine that makes proteins from messenger RNAs.

However, how the nucleolus grows and maintains its structure has puzzled scientists for some time. It turns out that even though it looks like a simple liquid blob, it's rather well-organized, consisting of three distinct layers: the fibrillar center, where the RNA polymerase is active; the dense fibrillar component, which is enriched in the protein fibrillarin; and the granular component, which contains a protein called nucleophosmin. Researchers have now discovered that this multilayer structure of the nucleolus arises from differences in how the proteins in each compartment mix with water and with each other. These differences let the proteins readily separate from each other into the three nucleolus compartments.

This photo of nucleolus proteins in the eggs of a commonly used lab animal, the frog Xenopus laevis, shows each of the nucleolus compartments (the granular component is shown in red, the fibrillarin in yellow-green, and the fibrillar center in blue). The researchers have found that these compartments spontaneously fuse with each other on encounter without mixing with the other compartments.

For more details on this research, see this press release from Princeton. Related to video 3789, video 3791 and image 3793.

A macrophage—a type of immune cell that engulfs invaders—“eats” and is activated by a “two-faced” Janus particle. The particle is called “two-faced” because each of its two hemispheres is coated with a different type of molecule, shown here in red and cyan. During macrophage activation, a transcription factor tagged with a green fluorescence protein (NF-κB) gradually moves from the cell’s cytoplasm into its nucleus and causes DNA transcription. The distribution of molecules on “two-faced” Janus particles can be altered to control the activation of immune cells. Details on this “geometric manipulation” strategy can be found in the Proceedings of the National Academy of Sciences paper "Geometrical reorganization of Dectin-1 and TLR2 on single phagosomes alters their synergistic immune signaling" by Li et al. and the Scientific Reports paper "Spatial organization of FcγR and TLR2/1 on phagosome membranes differentially regulates their synergistic and inhibitory receptor crosstalk" by Li et al. This video was captured using epi-fluorescence microscopy.

Related to video 6800.

Sensory organs have cells equipped for detecting signals from the environment, such as odors. Receptors in the membranes of nerve cells in the nose bind to odor molecules, triggering a cascade of chemical reactions tranferred by G proteins into the cytoplasm.

The interior of a regenerating lizard tail 14 days after the original tail was amputated. Cell nuclei (blue), proliferating cells (green), cartilage (red), and muscle (white) have been visualized with immunofluorescence staining.

The human skin cells pictured contain genetic modifications that make them pluripotent, essentially equivalent to embryonic stem cells. A scientific team from the University of Wisconsin-Madison including researchers Junying Yu, James Thomson, and their colleagues produced the transformation by introducing a set of four genes into human fibroblasts, skin cells that are easy to obtain and grow in culture.

This image shows the long, branched structures (axons) of nerve cells. Running horizontally across the middle of the photo is an axon wrapped in rings made of actin protein (green), which plays important roles in nerve cells. The image was captured with a powerful microscopy technique that allows scientists to see single molecules in living cells in real time. The technique is called stochastic optical reconstruction microscopy (STORM). It is based on technology so revolutionary that its developers earned the 2014 Nobel Prize in Chemistry. More information about this image can be found in: K. Xu, G. Zhong, X. Zhuang. Actin, spectrin and associated proteins form a periodic cytoskeleton structure in axons. Science 339, 452-456 (2013).

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

Video of high-resolution confocal images depicting vimentin immunofluorescence (green) and nuclei (blue) at the edge of a quail embryo yolk. These images were obtained as part of a study to understand cell migration in embryos. An NIGMS grant to Professor Garcia was used to purchase the confocal microscope that collected these images. Related to images 2807 and 2808.

Stereo triplet of a sea urchin embryo stained to reveal actin filaments (orange) and microtubules (blue). This image is part of a series of images: 1047, 1048, 1049, 1050 and 1051.

In this image of a stained fruit fly ovary, the ovary is packed with immature eggs (with DNA stained blue). The cytoskeleton (in pink) is a collection of fibers that gives a cell shape and support. The signal-transmitting molecules like STAT (in yellow) are common to reproductive processes in humans. Researchers used this image to show molecular staining and high-resolution imaging techniques to students.

This time-lapse movie shows that bacterial communities called biofilms can create blockages that prevent fluid flow in devices such as stents and catheters over a period of about 56 hours. This video was featured in a news release from Princeton University.

This image shows mouse fetal heart fibroblast cells. The muscle protein actin is stained red, and the cell nuclei are stained blue. The image was part of a study investigating stem cell-based approaches to repairing tissue damage after a heart attack. Image and caption information courtesy of the California Institute for Regenerative Medicine.

Colorized scanning electron micrographs progressively zoom in on the eye of a crab larva. In the higher-resolution frames, bacteria are visible on the eye.

DNA (blue) and actin (red) in cultured fibroblast cells.

Bacillus anthracis (anthrax) cells being killed by a fluorescent trans-translation inhibitor, which disrupts bacterial protein synthesis. The inhibitor is naturally fluorescent and looks blue when it is excited by ultraviolet light in the microscope. This is a color version of Image 3481.

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

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

For videos of cell-like compartments from frog eggs view: 6587, 6588, 6589, and 6590.

The plasma membrane is a cell's protective barrier. See image 2523 for an unlabeled version of this illustration. Featured in The Chemistry of Health.

A crane fly spermatocyte during metaphase of meiosis-I, a step in the production of sperm. A meiotic spindle pulls apart three pairs of autosomal chromosomes, along with a sex chromosome on the right. Tubular mitochondria surround the spindle and chromosomes. This video was captured with quantitative orientation-independent differential interference contrast and is a time lapse showing a 1-second image taken every 30 seconds over the course of 30 minutes.

More information about the research that produced this video can be found in the J. Biomed Opt. paper “Orientation-Independent Differential Interference Contrast (DIC) Microscopy and Its Combination with Orientation-Independent Polarization System” by Shribak et. al.

A replica of a human retina grown from stem cells. It shows rod photoreceptors (nerve cells responsible for dark vision) in green and red/green cones (nerve cells responsible for red and green color vision) in red. The cell nuclei are stained blue. This image was captured using a confocal microscope.

This tropical scene, reminiscent of a postcard from Key West, is actually a petri dish containing an artistic arrangement of genetically engineered bacteria. The image showcases eight of the fluorescent proteins created in the laboratory of the late Roger Y. Tsien, a cell biologist at the University of California, San Diego. Tsien, along with Osamu Shimomura of the Marine Biology Laboratory and Martin Chalfie of Columbia University, share the 2008 Nobel Prize in chemistry for their work on green fluorescent protein-a naturally glowing molecule from jellyfish that has become a powerful tool for studying molecules inside living cells.

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 mostly shows normal cultured epithelial cells expressing green fluorescent protein targeted to the Golgi apparatus (yellow-green) and stained for actin (magenta) and DNA (cyan). The middle cell is an abnormal large multinucleated cell. All the cells in this image have a Golgi but not all are expressing the targeted recombinant fluorescent protein.

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

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.

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.

Image showing that the edge zone (top of image) of the quail embryo shows no proliferating cells (cyan), unlike the interior zone (bottom of image). Non-proliferating cell nuclei are labeled green. This image was obtained as part of a study to understand cell migration in embryos. More specifically, cell proliferation at the edge of the embryo was studied by examining the cellular uptake of a chemical compound called BrDU, which incorporates into the DNA during the S-phase of the cell cycle. Here, the cells that are positive for BrDU uptake are labeled in cyan, while other non-proliferating cell nuclei are labeled green. Notice that the vast majority of BrDU+ cells are located far away from the edge, indicating that edge cells are mostly non-proliferating. An NIGMS grant to Professor Garcia was used to purchase the confocal microscope that collected this image. Related to image 2807 and video 2809.

Ovarioles in female insects are tubes in which egg cells (called oocytes) form at one end and complete their development as they reach the other end of the tube. This image, taken with a confocal microscope, shows ovarioles in a very popular lab animal, the fruit fly Drosophila. The basic structure of ovarioles supports very rapid egg production, with some insects (like termites) producing several thousand eggs per day. Each insect ovary typically contains four to eight ovarioles, but this number varies widely depending on the insect species.

Scientists use insect ovarioles, for example, to study the basic processes that help various insects, including those that cause disease (like some mosquitos and biting flies), reproduce very quickly.

In many animals, the egg cell develops alongside sister cells. These sister cells are called nurse cells in the fruit fly (Drosophila melanogaster), and their job is to “nurse” an immature egg cell, or oocyte. Toward the end of oocyte development, the nurse cells transfer all their contents into the oocyte in a process called nurse cell dumping. This process involves significant shape changes on the part of the nurse cells (blue), which are powered by wavelike activity of the protein myosin (red). This image was captured using a confocal laser scanning microscope. Related to video 6754.

Dictyostelium discoideum is a microscopic amoeba. A group of 100,000 form a mound as big as a grain of sand. Featured in The New Genetics.

Stained glomeruli in the kidney. The kidney is an essential organ responsible for disposing wastes from the body and for maintaining healthy ion levels in the blood. It works like a purifier by pulling break-down products of metabolism, such as urea and ammonium, from the bloodstream for excretion in urine. The glomerulus is a structure that helps filter the waste compounds from the blood. It consists of a network of capillaries enclosed within a Bowman's capsule of a nephron, which is the structure in which ions exit or re-enter the blood in the kidney.

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.

Cdc42, a member of the Rho family of small guanosine triphosphatase (GTPase) proteins, regulates multiple cell functions, including motility, proliferation, apoptosis, and cell morphology. In order to fulfill these diverse roles, the timing and location of Cdc42 activation must be tightly controlled. Klaus Hahn and his research group use special dyes designed to report protein conformational changes and interactions, here in living neutrophil cells. Warmer colors in this image indicate higher levels of activation. Cdc42 looks to be activated at cell protrusions.

Related to images 2452, 2453, and 2454.

This video results from a research project to visualize which regions of the adult fruit fly (Drosophila) brain derive from each neural stem cell. First, researchers collected several thousand fruit fly larvae and fluorescently stained a random stem cell in the brain of each. The idea was to create a population of larvae in which each of the 100 or so neural stem cells was labeled at least once. When the larvae grew to adults, the researchers examined the flies’ brains using confocal microscopy. With this technique, the part of a fly’s brain that derived from a single, labeled stem cell “lights up.” The scientists photographed each brain and digitally colorized its lit-up area. By combining thousands of such photos, they created a three-dimensional, color-coded map that shows which part of the Drosophila brain comes from each of its ~100 neural stem cells. In other words, each colored region shows which neurons are the progeny or “clones” of a single stem cell. This work established a hierarchical structure as well as nomenclature for the neurons in the Drosophila brain. Further research will relate functions to structures of the brain.

Related to images 5838 and 5868.

Body organs such as the liver and kidneys process chemicals and toxins. These "target" organs are susceptible to damage caused by these substances. See image 2496 for an unlabeled version of this illustration.