Differentiation in biology characterizes the transformation from a poorly differentiated to a highly differentiated state. This process has particular importance during the development of the fertilized egg into a complete organism. Disturbances in the differentiation process can lead to serious diseases such as cancer or malformations.
What is differentiation?
Biological differentiation is about the specialization of undifferentiated stem cells into differentiated somatic cells. Biological differentiation is about the specialization of undifferentiated stem cells into differentiated somatic cells. Especially during embryogenesis and subsequent growth, these processes play a prominent role. However, differentiation processes are still important for the maintenance of body functions in adult organisms. Initially, undifferentiated stem cells still possess the ability to transform into all other body cells. In the process, several differentiation processes give rise to specialized body cells, which form the various organs and eventually lose the ability to divide. There are several types of stem cells. For example, the so-called totipotent stem cells are still able to transform each into a complete organism. The pluripotent stem cells, in turn, can still differentiate into all body cells. However, it is no longer possible for them to develop into individual organisms. Multipotent stem cells have already achieved a certain differentiation into a specific cell line. However, they can still differentiate into all other cells of that cell lineage.
Function and task
Biological differentiation represents one of the most important processes in the development of plant, animal, or human organisms. During this process, among other things, increasingly highly differentiated somatic cells develop from a fertilized egg cell in several steps. The fertilized egg cell is the first totipotent stem cell, which initially undergoes cell division into four identical cells. Each of these four cells can develop into a complete genetically identical organism. When the four-cell stage is reached, formation of the blastocyst occurs, which consists of pluripotent embryonic stem cells. These pluripotent stem cells can develop through the next stage of differentiation into the three germ layers ectoderm, entoderm and mesoderm and thus represent the starting point for all further body cells. However, in contrast to totipotent stem cells, these have already lost the ability to develop into genetically identical independent organisms. The three cotyledons give rise to further cell lineages, which initially consist of multipotent stem cells. In this process, the multipotent stem cells are able to develop into all cell types of the respective cell lineage. These cells no longer possess the ability to transform into all other somatic cells, since they have already reached a higher degree of differentiation than the pluripotent stem cells. In animal and human organisms, the process of differentiation is associated with a determination. Determination refers to the specification of a specialization once it has been taken, with the further development of the cell lines being passed on by epigenetic means. Of course, cells that have already been pre-differentiated will continue to differentiate into the cells of the corresponding cell lineage as part of their determination. Although the overall genetic information of each cell is identical, it is called up differently by gene expression depending on the cell type. This means, among other things, that in a liver cell, for example, only the genetic information for liver function is decoded, while all other information remains unread. Differentiation is influenced by various external or internal factors. Hormones and growth factors, for example, play an important role. Cell contacts with neighboring cells also determine the direction of differentiation. Under certain conditions, transdetermination can occur. In this case, the cell determination is changed. This plays a role especially in wound healing. In these cases, if the cells are already differentiated, they lose their differentiation and differentiate again. However, if this process is disturbed, cancer can occur.Differentiation is essential for the organism to function at all as a unified biological system.
Diseases and disorders
However, during cell differentiation, disorders can occur that potentially lead to organ malformations during embryogenesis. Thus, there are some genetic diseases with multiple organ dysplasias. In addition to malformations of the internal organs, the external appearance is often disharmonious. However, there are also non-genetic causes of organ malformations. One example is renal agenesis in the absence of amniotic fluid. Since the human embryo can only develop within the amniotic fluid, defective organ differentiation occurs here due to the lack of space, and other organs and tissues are also affected. Drugs can also disrupt the differentiation process during embryogenesis. A well-known example is the tranquilizer thalidomide, which caused damage to the growth development of the fetus during early pregnancy. This became public in 1961 with the so-called thalidomide scandal. However, it can also happen that already differentiated cells de-differentiate and then multiply uncontrollably. This situation is present in cancer. The more advanced the de-differentiation of the cells, the more malignant the tumor. As mentioned earlier, de-differentiation is necessary in some cases when there is a greater need for cell growth. This is the case, among others, in wound healing. However, in these processes, de-differentiation is followed by cell differentiation again. However, if differentiation then fails to occur, cancer develops. Somatic mutations in cells may also affect genes that influence differentiation. Therefore, as we age, the likelihood of developing cancer increases.
