Histology & Its Methods of Study

DefinitionHistology (Gr. histo, web or tissue, + logos, study) is the study of the tissues of the body and of how these tissues are arranged to constitute organs. Four fundamental tissues are recognized: epithelial tissue, connective tissue, muscular tissue, and nervous tissue.

The most common procedure used in the study of tissues is the preparation of histological sections that can be studied with the aid of the light microscope Under the light microscope, tissues are examined via a light beam that is transmitted through the tissue

ReasonBecause tissues and organs are usually too thick for light to pass through them, they must be sectioned to obtain thin, translucent sections

is this currently howItat then possible to study

these structures for long periods and under varying physiological or experimental conditions. In most cases, however, tissues must be sliced into thin sections and attached on glass slides before they can be examined. These sections are precisely cut from tissues previously prepared for sectioning using fine cutting instruments

microtomes

microtomes mechanical instrument used to cut biological specimens into transparent thin sections for microscopic examination

Microtomes use steel, microtomes blades glass, or diamond depending upon the specimen being sliced and the desired thickness of the sections being cut. Steel blades are used to prepare sections of animal or plant tissues for light

microtomes

materials such as bone, teeth and plant matter for both light microscopy and for electron microscopy. Gem quality diamond knives are used for slicing thin sections for electron microscopy.

Glass knives are used to slice sections for light microscopy and to slice very thin sections for electron microscopy. Industrial grade diamond knives are used to slice hard

Traditional histological microtomes technique: tissues are hardened by replacing water with paraffin. The tissue is then cut in the microtome at thicknesses varying from 2 to 25 m (micrometers) thick. From there the tissue can be mounted on a microscope slide, stained with appropriate aqueous dye(s) after prior removal of the paraffin, and examined using

section procedure) water-rich tissues are hardened by freezing and cut in the frozen state with a freezing microtome or microtome-cryostat; sections are stained and examined with a

microtomes (Frozen Cryosection:

This technique is much faster microtomes than traditional histology (5 minutes vs 16 hours) and is used in conjunction with medical procedures to achieve a quick diagnosis. Cryosections can also be used in immunohistochemistry as freezing tissue stops degradation of tissue faster than using a fixative and does not alter or mask its chemical composition as