Category: M

A solution in which the number of grams of dissolved substance per liter equals its molecular weight, i.e. a solution of molarity 1 M. A solution containing a gram molecular weight or mole of the reagent dissolved in 1 L (1000 ml) of solution; designated 1 M.  

Failure of the mitral valve to close, allowing a reflux of blood from the left ventricle of the heart to the left atrium. It most often results from scarring of the mitral valve by rheumatic fever, but it can also develop as a complication of myocardial infarction or cardiomyopathies. It may occur as a congenital…

A person suffering from an infection in whom the symptoms and signs are so minimal that either there is no request for medical assistance or the doctor fails to make the diagnosis. The patient usually has partial immunity to the disease, but since the infecting organisms (pathogens) are of normal virulence, nonimmune contacts can be…

The first-stage larva of a parasitic fluke. Miracidia hatch from eggs released into water with the host’s excreta. They have cilia and swim about until they reach a snail. The miracidia then bore into the snail’s soft tissues and there continue their development as sporocysts. The ciliated free-swimming larva of a digenetic fluke. On emerging…

An instrument for cutting extremely thin slices of material that can be examined under a microscope. The material is usually embedded in a suitable medium, such as paraffin wax. A common type of microtome is a steel knife. A laboratory instrument for cutting sections of biological tissues for study under a microscope. It is widely…

The use of ultrasound waves generated inside the body from an extremely small source, such as the tip of a needle or a bubble within the tissues. This technique is used to obtain a picture of the fine structure of the neighboring tissues. It is a specialized form of ultrasonography.  

A small particle consisting of a piece of endoplasmic reticulum with ribosomes attached. Microsomes are formed when homogenized cells are centrifuged.  

An extremely fine tube from which minute volumes of liquid can be delivered. It can also be used to draw up minute quantities of liquid for examination. Using a micropipette it is possible to add or take away material from individual cells under the microscope. An extremely small pipette used for measuring small amounts of…

The manipulation of extremely small structures under the microscope, as in microdissection, or microsurgery. The use of minute instruments and magnification aids to perform surgical or other procedures on tissues.  

A measurement of the proportion of red blood cells in a volume of circulating blood. It is determined by taking a sample of the patient’s blood in a fine tube and spinning it in a centrifuge until settling is complete.