Histology

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. For this reason, the microscope is a fundamental tool.

The word histology comes from the Greek stories which means ‘fabric’, ‘pole’ or ‘rod’ (in the sense of ‘to stand’). include the suffix lodge, which means ‘study or science’. Therefore, histology studies the minimal structures that make up the organisms of living beings.

The histology applications they encompass related sciences and fields as diverse as anatomy, medicine, immunology, pathology, physiology, cytology, nutrition, biochemistry, genetics, forensic investigation, agriculture, and archaeology, among others.

branches of histology

Within histology, two fundamental branches are known: plant and animal histology.

plant histology

histology
View of plant tissue under the microscope. Stoma detail.

Plant histology deals with the analysis of plants, that is, living beings 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 tissueswhich include the parenchymal, supporting, protective, secretory, and conducting tissues.

It may interest you: Parenchyma.

animal histology

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 it is included in the histology of animals, since from the biological point of view human beings are part of the animal kingdom. However, it constitutes a specific area of ​​interest when it comes to health.

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Animal histology includes the study of the following tissues:

  • connective or connective tissuewhich brings together the varieties of cartilaginous tissue, bone tissue, adipose tissue and blood;
  • epithelial tissuewhich is the tissue that covers the surfaces of the body;
  • muscle tissueformed by cells that use chemical energy to generate movement;
  • nervous tissuewhich refers to the neurons that transmit useful information to the organism.

histological method

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

  1. Introductionin which the obtaining of the tissue takes place (for example, by means of a biopsy).
  2. Fixationa process that aims to preserve the characteristics of the fabric through various techniques.
  3. Inclusionmethod to harden the tissue in order to facilitate the cuts for the study by sections.
  4. Cutrefers to the process of cutting hardened tissues, which are executed with the help of an artifact called microtome.
  5. staining: it is a process that increases contrast through coloration, since many tissues are colorless under the microscope.
  6. Observation: refers to the process of observation and analysis carried out by the specialist through the microscope, from which it is possible to draw conclusions.

history of histology

histology

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

Marcello Malpighi (1628-1694), a researcher at the Academia del Cimento, Florence, was considered the father of histology because he first analyzed tissues using the microscope, 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.

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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 types of cells: prokaryotes and eukaryotes.

modern histology

In the eighteenth 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 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) was essential.

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

It may interest you Microscope.

Importance of histology

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

For example,

  • Identifies pathologies that affect health, either through pathogens (viruses and bacteria) as well as by imbalances in the body such as diabetes, high cholesterol, hemophilia, anemia, leukocytosis, etc.
  • It allows exploring hypotheses, identifying problems and solutions through tissue culture.
  • Promotes the development of agriculture.
  • Collaborate in criminal investigation processes.
  • Provides specialized information for archaeological research.

See also Branches of biology.