Dissecting Microscopes

Rodent Survival upon Surgery

dissectingmicroscopes — Thu, 28 Jun 2007 17:06:57 +0000

The article discussed the guidelines on rodent survival after its surgical operation. These guidelines were written based from the observations made from surgeries done on rodents at East Tennessee State University. The guidelines have been prepared and accepted by their committee on animal care to serve as source of knowledge for the qualified researchers and technical staff, and to function as an instruction manual for students and other people who have little or no experience on the field of experimental surgery. Other kinds of procedure being performed in experimental surgery, aside from the one laid down by the National Institutes for Health, must be brought to their attention for proper evaluation and approval of the committee on animal care.

The article stated the various procedures being performed before, during, and after the operations. Prior to the operation, the processes include isolated place for the aseptic or clean procedure. However, the aseptic procedure can also be done in a traditional laboratory provided the place is clean, properly disinfected and sanitized, and draped by sterile linens. The rodents shall be abstained from foods as part of the standard operating procedure of surgery. Moreover, such activity shall decrease their gastro-intestinal contents and will give additional intra-abdominal space for the surgeon.

(more…)

Dissecting Microscope

dissectingmicroscopes — Mon, 21 May 2007 05:01:01 +0000

A microscope is a device used to view objects too small for the unaided eye. Objects that are only seen through a microscope are microscopic, which means very small. Microscopes provide an enlarged image of a small object. It is impossible to say who invented the compound microscope. Dutch spectacle-makers Hans Janssen and his son Zacharias Janssen are often said to have invented the first compound microscope in 1590, but this was a declaration by Zacharias Janssen himself halfway through the 17th century. The date is certainly not likely, as it has been shown that Zacharias Janssen actually was born around 1590. Another favorite for the title of ‘inventor of the microscope’ was Galileo Galilei. He developed an occhiolino or compound microscope with a convex and a concave lens in 1609. Galilei’s microscope was celebrated in the ´Lynx academy´ founded by Federico Cesi in 1603. Francesco Stelluti’s drawing of three bees were part of pope Urban VIII´s seal, and count as the first microscopic figure published (see Stephen Jay Gould, The Lying stones of Marrakech, 2000). Christiaan Huygens, another Dutchman, developed a simple 2-lens ocular system in the late 1600s that was achromatically corrected and therefore a huge step forward in microscope development. The Huygens ocular is still being produced to this day, but suffers from a small field size, and the eye relief is uncomfortably close compared to modern widefield oculars. (more…)

How Dissecting Microscopes are Identified

dissectingmicroscopes — Mon, 21 May 2007 05:00:11 +0000

A simple microscope is a microscope that uses only one lens for magnification, and is the original light microscope. Van Leeuwenhoek’s microscopes consisted of a single, small, convex lens mounted on a plate with a mechanism to hold the material to be examined (the sample or specimen). Demonstrations by British microscopist Brian J. Ford have produced surprisingly detailed images from such basic instruments. The use of a single, convex lens to magnify objects for viewing is found today only in the magnifying glass, the hand-lens, and the loupe. The compound microscope uses a set of many lenses in order to maximize magnification. In its simplest form - as used by Robert Hooke, for example - the compound microscope would have a single glass lens of short focal length for the objective, and another single glass lens for the eyepiece or ocular. Modern microscopes of this kind are usually more complex, with multiple lens components in both objective and eyepiece assemblies. In modern microscopes the mirror is replaced by a lamp unit providing stable, controllable illumination. (more…)

The Dissecting Microscope and Forensics

dissectingmicroscopes — Mon, 21 May 2007 04:59:15 +0000

A dissecting microscope, sometimes known also as stereo microscope or comparison microscope, is a device used to analyze side-by-side specimens. It consists of two microscopes connected to an optical bridge, which results in a split view window. The dissecting microscope is used in forensic sciences to compare microscopic patterns and identify or deny their common origin. The idea behind the dissecting microscope is simple. Two microscopes are placed next to each other and the optical paths of each microscope are connected together by the optical bridge would help the forensic examiners to simultaneously compare two specimens instead of depending on their memory. The dissecting microscope had major roles in early forensics. Its history dates back to the 1920s where it was used in forensic ballistics. The accused murderers and anarchists Nicola Sacco and Bartolomeo Vanzetti was one such case. Dissecting microscope was used for ballistic identification evidence in 1921 to help secure convictions of accused murderers Sacco and Vanzetti. (more…)

Dissecting Microscopes and Forensics 2

dissectingmicroscopes — Mon, 21 May 2007 04:58:31 +0000

Handguns predominated as the firearm of choice in shooting-related crimes, especially in the United States of America. As with most firearms, the fired ammunition components may acquire sufficient unique and reproducible microscopic marks to be identifiable as having been fired by a single firearm. Making these comparisons is correctly referred to as firearms identification, or sometimes called as “ballistics”. Historically, and currently, this forensic discipline ultimately requires a microscopic side-by-side comparison of fired bullets or cartridge cases, one pair at a time, by a forensic examiner to confirm or possibly eliminate the two items as having been fired by a single firearm. For this purpose, the traditional tool of the firearms examiner has been what is often called the ballistics comparison microscope. Comparison microscope is essential for the forensic ballistics expert in comparing bullets and spent cartridge casings. (more…)

Modern Dissecting Microscopes

dissectingmicroscopes — Mon, 21 May 2007 04:57:15 +0000

Comparison of microscope has evolved, since the mid-1920s Sacco and Vanzetti Case, into an instrument with many optical, mechanical and electronic refinements, including fiber optic illumination, video capabilities, digital imaging, automatic exposure for conventional photography, etc. Despite this evolution, however, the basic tools and techniques have remained unchanged in their essential details which are to determine whether or not ammunition components were fired by a single firearm based on a sufficiency of unique and reproducible microscopic and class characteristics, or to reach a “no conclusion” result if insufficient marks are present. Since, ballistic identification has benefited from a long series of structural, scientific and technological advances, law enforcement agencies have established forensic labs and researchers have learned much more about how to match bullets and cartridge cases to the guns used to fire them, and comparison microscopes have become more sophisticated. (more…)

Brief introduction to dissecting microscopes

dissectingmicroscopes — Mon, 21 May 2007 04:56:05 +0000

A microscope is an instrument used to view small objects that cannot be seen by the naked or unaided eye. The science of investigating small objects using such an instrument is called microscopy and the term microscopic means minute or very small. Microscopes give us a large image of a tiny object. The microscopes we use in school and at home trace their history back almost 400 years. The first useful microscope was developed in the Netherlands in the early 1600s. There is no exact date as when it was invented. There is also confusion about who invented the first microscope. History credits three different eyeglass makers for the invention: Hans Lippershey, Hans Janssen, and his son, Zacharias Janssen. The most common type of microscope, and the first to be invented, is the optical microscope. The optical microscope is an instrument containing one or more lenses that produce an enlarged image of an object placed in the focal plane of the lens. There are, however, many other microscope designs. It can largely be separated into two classes, the optical theory microscopes and scanning probe microscopes. (more…)