Stem cells are key pieces for organisms. Thanks to them is that there is an embryonic development to produce complete organisms from two initial cells. It is also because of them that the body can repair itself. There are two types of classifications for stem cells: according to their origin and according to their potential. First we will review the one that corresponds to its origin.
Types of stem cells: Embryonic stem cell
They are found in the cell mass of embryos a few days old, specifically in the blastocyst stage. These stem cells are responsible for generating all types of tissues that make up the body’s organs. They are the stem cells that have the greatest potential because all types of cells can be formed from them to form a functional and complete organism.
They are found in tissues of adult organisms and assist during tissue repair . They are organ-specific and can only produce cells of the type of tissue they are in. There is a wide variety of adult stem cells, just as there are tissues. For example, there are in :
- Bone marrow
- Neural tube
Types of stem cells: They are given the same name as the tissue in which they are found . For example, there are pancreatic stem cells, cardiac stem cells, and so on.
Their differentiation capacity is more limited than in the case of embryonic stem cells, since they cannot generate complete individuals. Despite this, its function remains extremely important for the existence of organisms.
The second type of classification can within stem cells refers to their potential for differentiation. Below we explain each one.
Types of stem cells: They are of the embryonic type and have the capacity to form the embryo , the placental tropho-blast, which is the layer of cells that assists during the embryo’s nutrition, and the yolk sac that fulfills the excretory, respiratory, and nutritional functions of the embryo.
In other words, these cells are capable of forming a complete adult organism . Only the zygote, which is the union of the egg with the sperm, and the daughter cells of the first two divisions are of the toti-potential type. They are the stem cells with the most varied range of differentiation . We can imagine this classification of stem cells as a pyramid and this is the one that is at the top due to its great capacity for differentiation.
Types of stem cells: Pluripotential
Types of stem cells: It is also of the embryonic type and is the result of the differentiation of toti-potent stem cells . At four days of development, the totipotent cells differentiate into pluripotent cells in the blastocyst, which is the second stage during embryo development. They also differ in the inner cell mass of the embryo.
They can differentiate into the three germ layers of the embryo , which are also called cell lineages:
These cells have less capacity to differentiate compared to totipotential cells and cannot generate complete organisms.
Types of stem cells: Multi-potential
Types of stem cells: They can be embryonic or adult and are cells with a reduced capacity to form different cells . As we can see, as stem cells become more differentiated, they lose the ability to generate more ranges of cells.
These multi-potential cells are limited to the location of the cellular tissue . Those found in muscle can only produce muscle cells, those in the neural tube can only produce astrocytes, neurons, and oligodendrocytes, and so on.
On the other hand, they can only differentiate more specific cells as long as they are from the same embryonic layer . There are three types of layers, those already mentioned above, and different tissues are shed from each of them. From the ectoderm derives the nervous system and the skin, from the mesoderm the muscles, gonads, kidneys and bone system, from the endoderm derives the digestive system, the liver, the endocrine glands and the lungs.
The best known example of multi-potential cells are hematopoietic cells . Some of the characteristics of this multi-potential cell are:
- They are found within the bone marrow and generate the many blood cells that exist.
- They are built from a stem cell : during a long process of several precursors until the final result with particular activities to complete. This process is known as hematopoiesis.
- Some of these cells are basophils, eosinophils, B and T lymphocytes, macrophages, and erythrocytes .
It is important to mention that the study of all types of stem cells has led to great progress in the medical field , where their knowledge has a great application for therapies and treatment of multiple diseases.
Types of stem cells: They are the most specialized stem cells and can only produce cells of one type. Although they can only produce a single type of cell, they can self -renew . Examples of this are:
- Stem cells of the skin : found in the basement membrane of the interfollicular epidermis and from which only keratinized scales are produced.
- Spermatogonial stem cells : which are only capable of producing sperm.