Misplaced Pages

#117882

53-461: Eustachian , meaning "discovered by, described by or attributed to Eustachi " (Latin name Eustachius ) may refer to: Bartolomeo Eustachi Bartolomeo was born in San Severino in the province of Ancona, where his father, Marinao Eustachius, was a wealthy and prominent physician. Bartolomeo received the required broad humanistic education typical of that time, and then studied medicine at

106-493: A thinly sectioned sample to produce an observable image. Other major types of microscopes are the fluorescence microscope , electron microscope (both the transmission electron microscope and the scanning electron microscope ) and various types of scanning probe microscopes . Although objects resembling lenses date back 4,000 years and there are Greek accounts of the optical properties of water-filled spheres (5th century BC) followed by many centuries of writings on optics,

159-601: A 0.1 nm level of resolution, detailed views of viruses (20 – 300 nm) and a strand of DNA (2 nm in width) can be obtained. In contrast, the SEM has raster coils to scan the surface of bulk objects with a fine electron beam. Therefore, the specimen do not necessarily need to be sectioned, but coating with a nanometric metal or carbon layer may be needed for nonconductive samples. SEM allows fast surface imaging of samples, possibly in thin water vapor to prevent drying. The different types of scanning probe microscopes arise from

212-437: A compound light microscope depends on the quality and correct use of the condensor lens system to focus light on the specimen and the objective lens to capture the light from the specimen and form an image. Early instruments were limited until this principle was fully appreciated and developed from the late 19th to very early 20th century, and until electric lamps were available as light sources. In 1893 August Köhler developed

265-420: A fine probe, usually of silicon or silicon nitride, attached to a cantilever; the probe is scanned over the surface of the sample, and the forces that cause an interaction between the probe and the surface of the sample are measured and mapped. A near-field scanning optical microscope is similar to an AFM but its probe consists of a light source in an optical fiber covered with a tip that has usually an aperture for

318-584: A key principle of sample illumination, Köhler illumination , which is central to achieving the theoretical limits of resolution for the light microscope. This method of sample illumination produces even lighting and overcomes the limited contrast and resolution imposed by early techniques of sample illumination. Further developments in sample illumination came from the discovery of phase contrast by Frits Zernike in 1953, and differential interference contrast illumination by Georges Nomarski in 1955; both of which allow imaging of unstained, transparent samples. In

371-483: A molecular level in both live and fixed samples. The rise of fluorescence microscopy drove the development of a major modern microscope design, the confocal microscope . The principle was patented in 1957 by Marvin Minsky , although laser technology limited practical application of the technique. It was not until 1978 when Thomas and Christoph Cremer developed the first practical confocal laser scanning microscope and

424-409: A sample and produce images, either by sending a beam of light or electrons through a sample in its optical path , by detecting photon emissions from a sample, or by scanning across and a short distance from the surface of a sample using a probe. The most common microscope (and the first to be invented) is the optical microscope , which uses lenses to refract visible light that passed through

477-436: A sample. In a TEM the electrons pass through the sample, analogous to basic optical microscopy . This requires careful sample preparation, since electrons are scattered strongly by most materials. The samples must also be very thin (below 100 nm) in order for the electrons to pass through it. Cross-sections of cells stained with osmium and heavy metals reveal clear organelle membranes and proteins such as ribosomes. With

530-437: A very small glass ball lens between the holes in two metal plates riveted together, and with an adjustable-by-screws needle attached to mount the specimen. Then, Van Leeuwenhoek re-discovered red blood cells (after Jan Swammerdam ) and spermatozoa , and helped popularise the use of microscopes to view biological ultrastructure. On 9 October 1676, van Leeuwenhoek reported the discovery of micro-organisms. The performance of

583-427: Is a laboratory instrument used to examine objects that are too small to be seen by the naked eye . Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisible to the eye unless aided by a microscope. There are many types of microscopes, and they may be grouped in different ways. One way is to describe the method an instrument uses to interact with

SECTION 10

#1732851466118

636-456: Is based on the use of non-reflecting substrates for cross-polarized reflected light microscopy. Ultraviolet light enables the resolution of microscopic features as well as the imaging of samples that are transparent to the eye. Near infrared light can be used to visualize circuitry embedded in bonded silicon devices, since silicon is transparent in this region of wavelengths. In fluorescence microscopy many wavelengths of light ranging from

689-402: Is based on what interacts with the sample to generate the image, i.e., light or photons (optical microscopes), electrons (electron microscopes) or a probe (scanning probe microscopes). Alternatively, microscopes can be classified based on whether they analyze the sample via a scanning point (confocal optical microscopes, scanning electron microscopes and scanning probe microscopes) or analyze

742-422: Is illuminated with infrared photons, each of which is spatially correlated with an entangled partner in the visible band for efficient imaging by a photon-counting camera. The two major types of electron microscopes are transmission electron microscopes (TEMs) and scanning electron microscopes (SEMs). They both have series of electromagnetic and electrostatic lenses to focus a high energy beam of electrons on

795-411: Is limited by the wavelength of the radiation used to image the sample, where shorter wavelengths allow for a higher resolution. Scanning optical and electron microscopes, like the confocal microscope and scanning electron microscope, use lenses to focus a spot of light or electrons onto the sample then analyze the signals generated by the beam interacting with the sample. The point is then scanned over

848-486: The Accademia dei Lincei in 1625 (Galileo had called it the occhiolino 'little eye'). René Descartes ( Dioptrique , 1637) describes microscopes wherein a concave mirror, with its concavity towards the object, is used, in conjunction with a lens, for illuminating the object, which is mounted on a point fixing it at the focus of the mirror. The first detailed account of the microscopic anatomy of organic tissue based on

901-545: The Second World War . Ernst Ruska, working at Siemens , developed the first commercial transmission electron microscope and, in the 1950s, major scientific conferences on electron microscopy started being held. In 1965, the first commercial scanning electron microscope was developed by Professor Sir Charles Oatley and his postgraduate student Gary Stewart, and marketed by the Cambridge Instrument Company as

954-530: The adrenal glands (reported in 1563). His greatest work, which he was unable to publish, was his Anatomical Engravings . These were completed in 1552, nine years after Vesalius had published his magnum opus, De Humani Corporis Fabrica Libri Septem in Basel. Published in 1714 by Giovanni Maria Lancisi at the expense of Pope Clement XI , and again in 1744 by Cajetan Petrioli , and again in 1744 by Bernhard Siegfried Albinus , and subsequently at Bonn in 1790,

1007-512: The atomic force microscope , then Binnig's and Rohrer's Nobel Prize in Physics for the SPM. New types of scanning probe microscope have continued to be developed as the ability to machine ultra-fine probes and tips has advanced. The most recent developments in light microscope largely centre on the rise of fluorescence microscopy in biology . During the last decades of the 20th century, particularly in

1060-419: The quantum tunnelling phenomenon. They created a practical instrument, a scanning probe microscope from quantum tunnelling theory, that read very small forces exchanged between a probe and the surface of a sample. The probe approaches the surface so closely that electrons can flow continuously between probe and sample, making a current from surface to probe. The microscope was not initially well received due to

1113-501: The "Stereoscan". One of the latest discoveries made about using an electron microscope is the ability to identify a virus. Since this microscope produces a visible, clear image of small organelles, in an electron microscope there is no need for reagents to see the virus or harmful cells, resulting in a more efficient way to detect pathogens. From 1981 to 1983 Gerd Binnig and Heinrich Rohrer worked at IBM in Zürich , Switzerland to study

SECTION 20

#1732851466118

1166-720: The Archiginnasio della Sapienza in Rome. He was also well versed in Hebrew, Arabic, and Greek, which gave him access to original medical treatises written in those languages. As a physician, Eustachius enjoyed great prestige among the upper classes, having among his patients the Duke of Urbino, the Cardinal della Rovero, and the Duke of Terranova. He became a member of the Medical College of Rome and in 1549

1219-409: The application. Digital microscopy with very low light levels to avoid damage to vulnerable biological samples is available using sensitive photon-counting digital cameras. It has been demonstrated that a light source providing pairs of entangled photons may minimize the risk of damage to the most light-sensitive samples. In this application of ghost imaging to photon-sparse microscopy, the sample

1272-505: The circulatory system, including the lower vena cava and its valves (now known as the Eustachian valve). These works were organized and published (illustrated with eight plates) as Opscula Anatomica in 1564. Eustachius was deeply interested in understanding the anatomical structures of the human body through direct observation, instead of accepting the many a priori theories current among other physicians. His anatomical investigations into

1325-460: The complex nature of the underlying theoretical explanations. In 1984 Jerry Tersoff and D.R. Hamann, while at AT&T's Bell Laboratories in Murray Hill, New Jersey began publishing articles that tied theory to the experimental results obtained by the instrument. This was closely followed in 1985 with functioning commercial instruments, and in 1986 with Gerd Binnig, Quate, and Gerber's invention of

1378-425: The current is kept constant by computer movement of the tip and an image is formed by the recorded movements of the tip. Scanning acoustic microscopes use sound waves to measure variations in acoustic impedance. Similar to Sonar in principle, they are used for such jobs as detecting defects in the subsurfaces of materials including those found in integrated circuits. On February 4, 2013, Australian engineers built

1431-526: The diffraction limit is occurred from light or excitation, which makes the resolution must be doubled to become super saturated. Stefan Hell was awarded the 2014 Nobel Prize in Chemistry for the development of the STED technique, along with Eric Betzig and William Moerner who adapted fluorescence microscopy for single-molecule visualization. X-ray microscopes are instruments that use electromagnetic radiation usually in

1484-449: The earliest known use of simple microscopes ( magnifying glasses ) dates back to the widespread use of lenses in eyeglasses in the 13th century. The earliest known examples of compound microscopes, which combine an objective lens near the specimen with an eyepiece to view a real image , appeared in Europe around 1620. The inventor is unknown, even though many claims have been made over

1537-473: The early 20th century a significant alternative to the light microscope was developed, an instrument that uses a beam of electrons rather than light to generate an image. The German physicist, Ernst Ruska , working with electrical engineer Max Knoll , developed the first prototype electron microscope in 1931, a transmission electron microscope (TEM). The transmission electron microscope works on similar principles to an optical microscope but uses electrons in

1590-417: The engravings show that Eustachius had dissected with the greatest care and diligence, and had taken the utmost pains to give accurate views of the shape, size, and relative position of the organs of the human body. The first seven plates illustrate the history of the kidneys and some of the facts relating to the structure of the ear. The eighth represents the heart, the ramifications of the vena azygos , and

1643-451: The eye or on to another light detector. Mirror-based optical microscopes operate in the same manner. Typical magnification of a light microscope, assuming visible range light, is up to 1,250× with a theoretical resolution limit of around 0.250  micrometres or 250  nanometres . This limits practical magnification to ~1,500×. Specialized techniques (e.g., scanning confocal microscopy , Vertico SMI ) may exceed this magnification but

Eustachian - Misplaced Pages Continue

1696-416: The light to pass through. The microscope can capture either transmitted or reflected light to measure very localized optical properties of the surface, commonly of a biological specimen. Scanning tunneling microscopes have a metal tip with a single apical atom; the tip is attached to a tube through which a current flows. The tip is scanned over the surface of a conductive sample until a tunneling current flows;

1749-399: The lungs. The publication in 1665 of Robert Hooke 's Micrographia had a huge impact, largely because of its impressive illustrations. Hooke created tiny lenses of small glass globules made by fusing the ends of threads of spun glass. A significant contribution came from Antonie van Leeuwenhoek who achieved up to 300 times magnification using a simple single lens microscope. He sandwiched

1802-512: The many different types of interactions that occur when a small probe is scanned over and interacts with a specimen. These interactions or modes can be recorded or mapped as function of location on the surface to form a characterization map. The three most common types of scanning probe microscopes are atomic force microscopes (AFM), near-field scanning optical microscopes (NSOM or SNOM, scanning near-field optical microscopy), and scanning tunneling microscopes (STM). An atomic force microscope has

1855-494: The place of light and electromagnets in the place of glass lenses. Use of electrons, instead of light, allows for much higher resolution. Development of the transmission electron microscope was quickly followed in 1935 by the development of the scanning electron microscope by Max Knoll . Although TEMs were being used for research before WWII, and became popular afterwards, the SEM was not commercially available until 1965. Transmission electron microscopes became popular following

1908-491: The post- genomic era, many techniques for fluorescent staining of cellular structures were developed. The main groups of techniques involve targeted chemical staining of particular cell structures, for example, the chemical compound DAPI to label DNA , use of antibodies conjugated to fluorescent reporters, see immunofluorescence , and fluorescent proteins, such as green fluorescent protein . These techniques use these different fluorophores for analysis of cell structure at

1961-518: The resolution is diffraction limited. The use of shorter wavelengths of light, such as ultraviolet, is one way to improve the spatial resolution of the optical microscope, as are devices such as the near-field scanning optical microscope . Sarfus is a recent optical technique that increases the sensitivity of a standard optical microscope to a point where it is possible to directly visualize nanometric films (down to 0.3 nanometre) and isolated nano-objects (down to 2 nm-diameter). The technique

2014-404: The same resolution limit as the optical and electron microscopes described above. The most common type of microscope (and the first invented) is the optical microscope . This is an optical instrument containing one or more lenses producing an enlarged image of a sample placed in the focal plane. Optical microscopes have refractive glass (occasionally plastic or quartz ), to focus light on

2067-554: The sample all at once (wide field optical microscopes and transmission electron microscopes). Wide field optical microscopes and transmission electron microscopes both use the theory of lenses ( optics for light microscopes and electromagnet lenses for electron microscopes) in order to magnify the image generated by the passage of a wave transmitted through the sample, or reflected by the sample. The waves used are electromagnetic (in optical microscopes ) or electron beams (in electron microscopes ). Resolution in these microscopes

2120-541: The sample to analyze a rectangular region. Magnification of the image is achieved by displaying the data from scanning a physically small sample area on a relatively large screen. These microscopes have the same resolution limit as wide field optical, probe, and electron microscopes. Scanning probe microscopes also analyze a single point in the sample and then scan the probe over a rectangular sample region to build up an image. As these microscopes do not use electromagnetic or electron radiation for imaging they are not subject to

2173-495: The slide. This microscope technique made it possible to study the cell cycle in live cells. The traditional optical microscope has more recently evolved into the digital microscope . In addition to, or instead of, directly viewing the object through the eyepieces , a type of sensor similar to those used in a digital camera is used to obtain an image, which is then displayed on a computer monitor. These sensors may use CMOS or charge-coupled device (CCD) technology, depending on

Eustachian - Misplaced Pages Continue

2226-560: The soft X-ray band to image objects. Technological advances in X-ray lens optics in the early 1970s made the instrument a viable imaging choice. They are often used in tomography (see micro-computed tomography ) to produce three dimensional images of objects, including biological materials that have not been chemically fixed. Currently research is being done to improve optics for hard X-rays which have greater penetrating power. Microscopes can be separated into several different classes. One grouping

2279-428: The study of comparative anatomy. He attempted to derive the physiology of organs on the basis of their anatomy. He did not restrict himself to gross anatomy: what was too minute for unassisted vision he inspected by means of glasses (early microscopes ). Structure that could not be understood in their pristine state he unfolded by maceration in different fluids, or rendered more distinct by injection and exsiccation. He

2332-458: The technique rapidly gained popularity through the 1980s. Much current research (in the early 21st century) on optical microscope techniques is focused on development of superresolution analysis of fluorescently labelled samples. Structured illumination can improve resolution by around two to four times and techniques like stimulated emission depletion (STED) microscopy are approaching the resolution of electron microscopes. This occurs because

2385-435: The ultraviolet to the visible can be used to cause samples to fluoresce , which allows viewing by eye or with specifically sensitive cameras. Phase-contrast microscopy is an optical microscopic illumination technique in which small phase shifts in the light passing through a transparent specimen are converted into amplitude or contrast changes in the image. The use of phase contrast does not require staining to view

2438-599: The use of a microscope did not appear until 1644, in Giambattista Odierna's L'occhio della mosca , or The Fly's Eye . The microscope was still largely a novelty until the 1660s and 1670s when naturalists in Italy, the Netherlands and England began using them to study biology. Italian scientist Marcello Malpighi , called the father of histology by some historians of biology, began his analysis of biological structures with

2491-410: The valve of the vena cava , named after the author. The seven subsequent plates offer different views of the viscera of the chest and abdomen. The seventeenth contains the brain and spinal cord; and the eighteenth more accurate views of the origin, course, and distribution of the nerves than had been given before. Fourteen plates are devoted to the muscles. Eustachius did not confine his researches to

2544-470: The vena caval Eustachian valve, led him to conclude that its function was to avoid reflux of blood. He also discovered the thoracic canal. Trying to understand how diseases affected body structures, Eustachius made comparative anatomical analysis of healthy and disease-altered organs (pathological anatomy). Working with Pier Matteo Pini, he produced a series of 47 detailed drawings of the studied organs. This series of illustrations, Tabulae Anatomicae Clariviri ,

2597-482: The years. Several revolve around the spectacle-making centers in the Netherlands , including claims it was invented in 1590 by Zacharias Janssen (claim made by his son) or Zacharias' father, Hans Martens, or both, claims it was invented by their neighbor and rival spectacle maker, Hans Lippershey (who applied for the first telescope patent in 1608), and claims it was invented by expatriate Cornelis Drebbel , who

2650-586: Was appointed Professor of Anatomy at the Papal College, the Archiginnasio dell Sapienza . He soon obtained papal dispensation to dissect cadavers from patients from the Santo Spirito Hospital. During 1562 and 1563 Bartolomeo Eustachio (writing under the Latin surname Eustacius) wrote a remarkable series of scientific works on the anatomy of the kidney, the hearing apparatus, the teeth and their structure, and

2703-567: Was known as a supporter of the 2nd century AD Roman anatomist Galen , entering into a public dispute with the eminent contemporary anatomist, Vesalius . However, both made their anatomic observations from dissection of human cadavers. Eustachius died in Umbria in 1574, during a trip to meet Cardinal della Rovere. Microscopes A microscope (from Ancient Greek μικρός ( mikrós )  'small' and σκοπέω ( skopéō )  'to look (at); examine, inspect')

SECTION 50

#1732851466118

2756-477: Was noted to have a version in London in 1619. Galileo Galilei (also sometimes cited as compound microscope inventor) seems to have found after 1610 that he could close focus his telescope to view small objects and, after seeing a compound microscope built by Drebbel exhibited in Rome in 1624, built his own improved version. Giovanni Faber coined the name microscope for the compound microscope Galileo submitted to

2809-504: Was published in 1714. Eustachio extended knowledge of the internal ear by rediscovering and describing correctly the Eustachian tube that bears his name. He was the first to describe the internal and anterior muscles of the malleus and the stapedius , and the complicated figure of the cochlea . He was the first to study accurately the anatomy of the teeth, and the phenomena of the first and second dentitions. Eustachius also discovered

#117882