Scanning electron micrograph of a seed from a bird-of-paradise flower (Strelitzia reginae). This plant is native to South Africa and has a distinctive orange and blue flower, which resembles an exotic bird. The seed was originally bought to become the study of a watercolour painting by Annie Cavanagh, but Dave McCarthy's interest in it produced this stunning image.



(Image: Annie Cavanagh & Dave McCarthy)

Copolymers can be used in microparticle or "particle-in-particle" drug delivery. Polymers that do not dissolve in acidic solutions can be used to coat a drug to prevent it being released in the stomach; or slowly dissolving polymers can slowly release a drug, reducing the number of times a day a person has to take medication.



The inner particle, shown here in orange, is loaded with the drug prednisolone, used to treat inflammatory bowel disease. The outer particle, in blue, is the copolymer that encapsulates it.



(Image: Annie Cavanagh)

This image captures the moment of human conception from an in vitro fertilisation (IVF) procedure.



The ovum (brown) is much larger than the sperm and is surrounded by protective cumulus cells (yellow). The membrane surrounding the ovum is the zona pellucida. The head of the sperm carries enzymes to dissolve the zona pellucida, allowing it to fertilise the egg.



(Image: M. I. Walker) Advertisement

This light microscope image by Spike Walker is of blood capillaries in the ciliary body of an ox's eye: the tiny holes that secrete a liquid called aqueous humour are shown. This liquid provides most of the nutrients for the lens and cornea.



This image was created from a stack of 27 images taken at different depths and combined to give a three-dimensional appearance. The capillaries have been made visible by injecting an insoluble dye into the artery.



(Image: M. I. Walker)

This image shows sensory nerve endings at the end of a hair follicle. Sensory nerves respond to stimuli to communicate movement, pressure and pain. The colours in this image were created by treating the tissue with silver nitrate and then processing it like photographic film. The nerve axons are stained black.



(Image: M. I. Walker

In his fourth image Spike Walker has made even the mundane look beautiful. This image of aspirin crystals was taken using a light microscope. Aspirin is not just used as a painkiller and anti-inflammatory, it also has anticoagulant properties.



(Image: M. I. Walker)

Another image by Spike Walker shows plankton. In this image he uses Rheinberg illumination, whereby coloured discs are used to provide vibrant colours, making fast-moving plankton visible against a brilliant blue background.



Plankton are small organisms, plant or animal, that drift in the sea with little or no locomotive ability. They are split into two main categories: phytoplankton, which are plant plankton that drift close to the surface and rely on photosynthesis for energy; and zooplankton, which are animals and include small protozoans or metazoans that normally feed on other plankton.



(Image: M. I. Walker)

The object of study in this image comes from a burn that the artist, Anne Weston, received from boiling soup spilt on her hand. The burn-damaged skin cells are shown under a scanning electron microscope. This kind of curiosity is important in image-making as "you never know what you are going to find", says Weston.



(Image: Anne Weston)

This scanning electron micrograph was also produced by Anne Weston. It shows a single cell grown from a culture of lung cancer cells. The irregular purple bulges are called blebs, a localised decoupling of the cytoskeleton from the plasma membrane caused by the cancer.



Blebbing is important in a variety of cellular processes including cell locomotion, cell division and physical or chemical stresses.



(Image: Anne Weston)

This image shows two red blood cells. A normal red blood cell is shown as a background to a red blood cell affected by sickle-cell anaemia.



Sickle-cell anaemia is a blood disease that causes the cell to form this characteristic shape, which affects its ability to carry haemoglobin. It is a genetic disorder caused when a person has two copies of a certain gene. It is common in countries where malaria is prevalent, as carrying one copy of the sickle-cell gene provides resistance to malaria.



(Image: Jackie Lewin/EM Unit/UCL Medical School)

This image shows the internal structure of a mouse liver, helping to understand this complex organ. Sinusoids – blood vessels – can be seen as pink structures running through the tissue. These contain red blood cells and Kupffer cells, which are specialist macrophages of the liver. Liver cells, or hepatocytes, shown in brown, are arranged in plates surrounding the sinusoids.



Bile is secreted into the passages known as canaliculi, shown as green channels. They are dilated intercellular spaces between hepatocytes, and bile flows through them en route to the small intestine.



(Image: Jackie Lewin)

This 3D image of a developing mouse head at an early embryonic stage was created using high-resolution episcopic microscopy (HREM). In HREM, samples are embedded in a plastic that has been stained with eosin, a fluorescent dye. A microtome is used to slice away fine sections of the sample – as thin as 2 microns – then an image of the remaining block is captured after each slice is taken.



Using computer software, different structures within the head can be visualised. Colour channels can be added to the 3D reconstruction to highlight tissue density, as shown here.



(Image: NIMR, MRC)

This 3D reconstruction of the lining of a mouse's small intestine was made using multiphoton fluorescent methods. Villi are small finger-like projections in the lining that increase surface area and so assist digestion. By combining stacked images, Paul Appleton and his colleagues were able to investigate the changes that colon cancer causes in the intestines.



(Image: Paul Appleton)

This image of compact bone from a human femur shows a network of tiny canals that contain blood vessels and connective tissue. Compact bone provides strength and rigidity in the body, and is composed of a layered matrix of organic substances and inorganic salts.



Living bone cells are destroyed during specimen preparation, leaving tiny holes. Air is often trapped inside these holes, giving the cavities a dark appearance because of optical refraction.



(Image: Ivor Mason)

This photo is of Harold Kroto, taken the day after his Nobel prize for chemistry was announced in 1996. He won the award, along with Robert Curl and Richard Smalley, for their discovery of the 60-atom clusters of carbon known as buckyballs and other fullerenes, models of which are shown in the foreground.



(Image: Anne-Katrin Purkiss)

This photograph was taken in the remote Tibetan Autonomous Region, China, in 2003. It shows a doctor standing on the roof of his house and holding two precious medical books: a copy of the Tibetan medical classic Gyu Shi (Four Tantras), written in the 12th century, and a manuscript on medicines that was composed by members of his medical family.



(Image: Theresia Hofer)

This image was commissioned for a leaflet produced to inform and reassure parents of premature babies. The ventilator allows the child to breathe efficiently while a saturation monitor checks that the oxygen concentration in the bloodstream is satisfactory. ECG monitoring apparatus ensures that the heart rate remains constant.



Possibly more pertinent than all the medical equipment is the presence of the child's blanket and teddy bear, showing that comfort is equally important.



(Image: Wellcome Photo Library)

This illustration by Bill McConkey depicts a mechanical heart connected to the pipes and valves of brass musical instruments: the artist has interpreted the heart as an ornate machine. The valves in this image were created from photographs of brass instruments and collaged digitally; the heart itself was originally a pencil drawing that was digitally textured and painted until it looked metallic.



(Image: Bill McConkey)