What is Histology?

Meaning

Histology means the science of the tissues.

histos is greek for web or tissue
logia is greek for branch of learning

Tissue was first used to describe the different textures of body parts being dissected by an anatomist.

This topic covers some background material that will help you understand the sections/pictures that you will be looking at in the other topics.

Introduction

All body parts are made up of four basic tissues:

Epithelial tissue
Connective tissue
Muscle
Nervous tissue

The properties of these four basic tissue types are covered in the topic on ‘tissue types‘.

Tissues are made up of

cells
extracellular (outside cells) matrix
body fluids

The basic properties of cells is covered in the topic ‘cells‘.

The extracellular material, or matrix is made by cells in the matrix. Some extracellular material is very strong, such as bone. Extracellular matrix is covered in the topic on tissue types ‘extracellular matrix‘.

Body fluids are made up of blood, interstitial fluid and lymph. You can find out more about blood in the topic ‘blood‘. You can find out more about interstitial fluid and lymph in the topic ‘lymphoid tissues‘.

Histological methods are used to study the detailed structures of tissues.

Most cells are colourless and transparent, and therefore histological sections have to be stained in some way to make the cells visible. The techniques used may either be non-specific, staining most fo the cells in much the same way, or specific, selectively staining particular chemical groupings or molecules within cells or tissues.

See the topic ‘How to make histological sections‘ to find out how histological sections are made, and cells can be stained.

Objectives

After following this topic, you should be able to

Define histology, and understand what tissues consist of.
Describe how histological sections are made for the light and electron microscopes.
Understand the difference between acidophilic and basophilic staining, and learn about some other types of staining.
Describe the differences between a light microscope and an electron microscope.