1 What is histology?
Histology is the study of tissues and their structure. The structure of each tissue is directly related to its function, so histology is related to anatomy and physiology.
Similarly, histopathology is the study of tissues affected by disease. This is something that can be very useful in making a diagnosis and in determining the severity and progress of a condition. Disease processes affect tissues in distinctive ways, which depend on the type of tissue, the disease itself and how it has progressed.
Histopathology units are found in most hospitals and there are also independent private laboratories. The services provided by these laboratories can be accessed by healthcare professionals, such as general practitioners (GPs).
Because of the great variety of tests that are available, and the high level of skill that is needed to carry them out and interpret them, many laboratories specialise in particular tissues or types of diagnosis. For example, a neuropathology laboratory will focus on understanding diseases that affect the nervous system.
Histology is also used extensively in biomedical research, to identify the causes and possible treatments for disease. This type of research may take place in a hospital laboratory but it is more often carried out in universities, research institutes and pharmaceutical companies.
The conventional view of a histopathologist is someone looking down a microscope. Most histological work does indeed involve the preparation of tissues for microscopy, observation of sections and reporting of the findings. However, a pathologist can often tell a great deal about a tissue without using a microscope.
For example, the brain of a person affected by multiple sclerosis has distinct lesions (areas of damage or injury) that are a few millimetres across. These are called plaques, and can readily be seen in a tissue sample with the human eye (see the darker areas highlighted with arrows in Figure 1 below).
Such large specimens that can be examined macroscopically (by eye) are usually only available post-mortem (after death) or following surgical removal of tissue. In contrast, biopsy specimens, which consist of just a needleful of cells or a flake of tissue, can be extracted at any time, but can only be examined microscopically.
In this course we will first teach you how to use a basic light microscope and then show some sections of various human tissues, presented via a virtual microscope, which mirrors the functions of a real microscope.
Once you are familiar with the normal appearance of different tissues, we will start to introduce sections from diseased tissues, and relate their appearance to the normal physiology of the tissue and pathological changes that have occurred.
Note that the virtual microscope tool will work in all modern browsers on desktop computers, laptops and tablet devices. However, we recommend completing the course on a desktop computer or laptop for better viewing of the sections and to enable integration of microscopy with the course text, images and video in separate windows.