Histology: what it is, what it studies and its history

What is histology?

Histology is a branch of biology that studies the organic tissues of animals and plants in their microscopic aspects: characteristics, composition, structure and function. Therefore, the microscope is the fundamental tool.

The word histology comes from the Greek histós which means 'tissue', 'pole' or 'rod' (in the sense of "standing"). Includes the suffix lodge , which means 'study or science'. Therefore, histology studies the minimal structures that make up the organisms of living beings.

The applications histology include related sciences and fields as diverse as anatomy, medicine, immunology, pathology, physiology, cytology, nutrition, biochemistry, genetics, forensics, agriculture and archeology, among others.

Branches of histology

Two fundamental branches are known within histology: plant and animal histology.

Plant histology

Plant tissue view under the microscope. Stoma detail.

Plant histology deals with the analysis of plants, that is, living things that belong to the plant kingdom. Plant histology comprises the study of two fundamental tissues:

• meristematic tissues (growth tissues), which include primary and secondary tissues; adult tissues, including parenchymal, supportive, protective, secretory, and conducting tissues.

It may interest you: Parenchyma.

Animal histology

View of human tissue under the microscope. Blood sample (detail of lymphocytes).

Animal histology studies metazoans, that is, animal living beings.

The human histology is included in the histology of the animals, as from the biological point of view humans are part of the animal kingdom. However, it constitutes a specific area of ​​interest in terms of health.

Animal histology includes the study of the following tissues:

• connective or connective tissue, which brings together the varieties of cartilage tissue, bone tissue, adipose tissue and blood; epithelial tissue, which is the tissue that lines the body's surfaces; muscle tissue, made up of cells that use chemical energy to generate movement; nervous tissue, which refers to neurons that transmit useful information to the body.

Histological method

The histological process refers to the histology techniques necessary to study the tissues. It is based on a series of elementary steps.

1. Introduction, in which the tissue is obtained (for example, by means of a biopsy). Fixation, a process that aims to preserve the characteristics of the tissue using various techniques. Inclusion, a method of stiffening tissue to facilitate cuts for sectional study. Cutting refers to the process of cutting hardened tissues, which are executed with the help of an artifact called a microtome. Staining: it is a process that increases contrast by means of staining, since many tissues are colorless under the microscope. Observation: refers to the observation and analysis process carried out by the specialist through the microscope, from which it is possible to draw conclusions.

Histology history

From left right: the first microscope and its inventor Zaccharias Janssen; Marcello Malpighi and Xavier Bichat.

Marcello Malpighi (1628-1694), a researcher at the Accademia del Cimento, Florence, was considered the father of histology because he analyzed tissues using the microscope for the first time, invented in the 16th century by Zaccharias Janssen. At the same time, Robert Hooke would do the same and manage to identify the existence of cells for the first time.

The microscope was improved in the 17th century by Anton van Leeuwenhoek, who achieved a magnification of 500x, thanks to which he was able to distinguish two different cell types: prokaryotes and eukaryotes.

Modern histology

In the 18th century, MF Xavier Bichat was designated the father of modern histology, being able to classify tissues and identify the microscopic origin of diseases.

In the 19th century, the recognition of the cell was essential as the minimum unit of living beings (H. Dutrochet, JP Müller and PJ François Turpin) and as the structural and functional unit of organisms (FT Schwann and M. Schleiden).

In the 20th century, 1931, Erns Ruska invented the electron microscope at 5000x magnification, which expanded histology to higher levels.

It may interest you Microscope.

Importance of histology

Histology is of vital importance to know the functioning of living organisms, which has repercussions in medical and scientific research in general and, even, in the economy.

For example,

• Identifies pathologies that affect health, either through pathogens (viruses and bacteria) as well as by body imbalances such as diabetes, high cholesterol, hemophilia, anemia, leukocytosis, etc. It allows to explore hypotheses, identify problems and solutions by cultivating tissues.Improves the development of agriculture.Collaborates in criminal investigation processes.It provides specialized information for archaeological investigation.