We explain what histology is and the topics that this discipline studies. In addition, plant histology, animal and importance.
What is histology?
Histology is a discipline that is part of biology and examines the tissues of organisms through a microscope to know their structure and functions. It is also referred to as microscopic anatomy or micro anatom a . The word histology comes from the Greek, histo which means weave and logos, which means knowledge .
Marcello Malpighi, an Italian anatomist and biologist, is considered the founder of histology for having been the first to examine living cells through a microscope in the early 17th century. Malpighi was the one who discovered the existence of small units within the tissues, called cells.
See also: Multicellular Organisms.
What does histology study?
Histology studies the microscopic structure of tissues, that is, complex clusters of organized cells to fulfill a certain function. The human being, for example, originates from the fusion of two cells: an ovule and a sperm. Both cells, in turn, then divide repeatedly to form new cells that make up the different tissues, organs and systems of the human body. Histological examinations allow us to know how the various components of the organism are organized, interrelated and functioning.
Histological exams provide important contributions to:
- Histopathology It is the part of histology that examines tissue samples taken from a diseased organism to learn more about the possible causes of the disease and provide a more accurate diagnosis.
- Forensic investigations and autopsies. The analysis of biological tissues, through special techniques, can clarify the causes of unexpected deaths and provide scientific evidence available to justice.
- The arqueology. By examining the cells and biological tissues found in remains recovered from ancient societies, information about their history can be obtained.
- The education. The basic histology techniques are taught in laboratory workshops to introduce students to the concept of microstructures of the different organisms.
From the general biology the existence of two groups of organisms is recognized: vascular plants (of the plantae kingdom) and animals (of the animal kingdom). From that distinction, histology is subdivided into plant histology and animal histology to categorize the different tissues.
Plant histology is the specific study of plant tissues that are classified into two types:
- Meristematic or embryonic tissues. They consist of small cells that have a great capacity to multiply.
- Adult tissues. They are those permanent or of duration in the plant and are composed of cells larger than the embryonic ones. These, in turn, can be:
- Parenchymal tissues. They consist of cells that are responsible for the nutrition and accumulation of reserves.
- Surface protection fabrics. They consist of cells that cover the plant and insulate it from the external environment.
- Supporting fabrics or colquenchymes. They are composed of thick-walled and elongated cells that give the plant stiffness.
- Conductive or vascular tissues. They are formed by cylindrical cells that join and form tubes or ducts, where nutrients circulate.
- Secretory and excretory tissues. They are formed by cells that secrete substances from the plant, such as the resin of the pine trees.
Animal histology studies the organic tissues of animals that, unlike the plant kingdom, have cells that form very diverse organisms in terms of their shape and function. Animal tissues are classified into four types:
- Epithelial tissues. They constitute several layers of cells joined together that form a cell membrane that covers all surfaces of the organism (such as the epidermis, digestive and respiratory tracts) and internal cavities (such as arteries, veins and capillaries).
- Connective or connective tissues. They contain cells in a varied way together with a viscous material that separates them from each other, called “intercellular substance”, which allows to join the other tissues to provide support and integration, for example, to adipose tissue, cartilaginous, bone and blood .
- Muscle tissues. They are formed by elongated cells called "muscle fibers", which contain myofibrils capable of contracting and giving elasticity to the muscles. According to the form and type of contraction, the muscles are classified as skeletal, cardiac and smooth.
- Nervous tissues. They are composed of cells called "neurons" that establish a complex connection system and have the ability to regenerate extremely slowly. They function as stimulus receptors (sensory neurons) to those that respond with nerve impulses (motor neurons) that propagate successively to other neurons (association neurons).
Importance of histology
The study of histology allows to know the structure and function of the organs through the microscopic examination of the cells that make them up. The results of histological studies are key to medicine and biology, both to know the body's properties under normal conditions and to examine the presence of pathologies, their evolution and their possible diagnosis.