Histology

Histology is the scientific discipline that focuses on the microscopic study of the anatomical structures of plant and animal cells and tissues. This branch of biology and medicine is derived from the Greek words "ἱστός" (histos, meaning "tissue") and "-λογία" (-logia, meaning "science"). It plays a crucial role in understanding the organization and function of biological tissues, as well as diagnosing various diseases.

Skin

Histology of decidua

Mesoderm

Overview

Histological analysis involves the examination of thin sections of cells and tissues under a light microscope or electron microscope. This process typically entails the sectioning and staining of specimens to highlight specific cellular structures and components, making them more readily observable. Histological studies can be conducted using tissue culture techniques, wherein live cells are isolated and maintained in an appropriate environment outside the body for research purposes.

The use of histological stains often enhances the visualization and differentiation of microscopic structures, which is vital for accurate identification and diagnosis. Histology serves as an indispensable tool for both biology and medicine, particularly in the diagnosis of diseases, such as cancer.

Histopathology

Histopathology is the microscopic examination of diseased tissue and is an essential component of anatomical pathology. Accurate diagnosis of cancer and other diseases typically necessitates histopathological analysis of samples. Board-certified pathologists or similarly trained physicians perform histopathological examinations and provide diagnostic information based on their findings.

Histotechnology

The preparation of histological sections is carried out by specialized professionals known as histotechnicians, histology technicians (HT), histology technologists (HTL), medical scientists, medical laboratory technicians, or biomedical scientists. Their field of study is referred to as histotechnology, which encompasses a range of techniques and skills required for the processing, sectioning, and staining of biological specimens.

Techniques in Histology

Histological techniques can be broadly divided into the following categories:

Fixation

Fixation is the process of preserving the structure of cells and tissues by using chemical fixatives, such as formalin. This step prevents tissue decomposition and maintains cellular structures for further examination.

Embedding

Embedding involves the infiltration of tissues with a supportive medium, such as paraffin wax or resin. This provides a firm matrix that allows for the creation of thin, uniform sections using a microtome.

Sectioning

Sectioning is the process of slicing the embedded tissue into thin sections using a microtome. These sections are then mounted onto glass slides for staining and microscopic examination.

Staining

Staining employs the use of various dyes to highlight specific cellular structures and components, making them more easily discernible under a microscope. Commonly used histological stains include hematoxylin and eosin (H&E), periodic acid-Schiff (PAS), and Masson's trichrome.

Microscopy

Microscopy involves the examination of histological sections using either a light microscope or electron microscope, depending on the level of detail and resolution required. This step allows researchers and clinicians to observe and analyze cellular structures and tissue organization.

Histology Resources
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