Determination is a step in cell differentiation, contributing to the specialization of tissues. The process establishes a developmental program for subsequent cells and deprives omnipotent cells of the ability to generate different cell types. The more specialized a tissue is, the smaller its regenerative capacity.
What is determination?
Determination is a step in differentiation and gives organisms their shape by contributing to the specialization of cells and tissues. Developmental biology tracks the evolution of cells and tissues into a more specialized state. In this development, the individual cells of a tissue undergo many changes until they reach specialization. The change can occur in several directions and is irreversible. Differentiation and cell division thus give a multicellular organism its form. The totality of this shaping process is called morphogenesis. The fertilized egg cell is the starting point of morphogenesis. In the course of differentiation processes, it becomes a complex structure of different cell types and tissue types. The zygote has totipotency. It is therefore capable of forming all cell types of the organism. Individual daughter cells develop from the zygote through cell division. These daughter cells specialize in certain roles depending on their lineage. This cell division step is accompanied by the so-called determination. The direction of specialization is epigenetically transmitted to all subsequent cell generations. Consequently, the determination sets the developmental program of subsequent cells.
Function and task
Determination is a step in differentiation and gives organisms their shape by contributing to the specialization of cells and tissues. This specialization occurs during embryogenesis to help determine the investment patterns of cells and tissues. Presumably, the determination is realized by the activation of the respective gene set. Developmental biology distinguishes between stable and labile determination. A determined cell always maintains its developmental program. This is true even if it migrates from the original site to another place in the organism or is transplanted there. The potency of a particular cell lineage is further and further limited by determinacy. The pluripotent stem cells of the embryo can still give rise to any cell type. Multipotent somatic stem cells can no longer give rise to all but only cell types of a tissue. At the end of the determination process are the irreversibly differentiated and functional somatic cells, which often no longer have the ability to divide and have only a limited lifespan. Determination can take place in different directions. That is, cells can change determination under certain circumstances. This process is also called transdetermination. In this process, the cells lose their differentiation, i.e. they dedifferentiate. After dedifferentiation, they can redifferentiate under certain circumstances. The new differentiation is then called transdifferentiation. These phenomena are involved in wound healing and carcinogenesis. Plants differ from animals in terms of determination and differentiation. They have meristematic cells specialized for division and generation of new tissues. Differentiated cells in plants, however, unlike in animals, are often not determinate or have limited programming. Thus, most plant cells retain the ability to divide and generate different cell types.
Diseases and disorders
The more differentiated a particular tissue is, the more poorly it recovers from damage and injury. Total regeneration can only occur in tissues capable of cell division. Thus, the regenerative capacity of an injured tissue depends on the degree of specialization. Regeneration can be complete, incomplete, or absent. With increasing differentiation, the regenerative capacity decreases. In nervous tissue and in the tissues of the heart, for example, myocardial cells and nerve cells with a particularly high degree of specialization are found. These cells can no longer divide. After damage to the heart or the central nervous system, therefore, only defect healing occurs. In contrast, blood cells and epithelial cells are less differentiated.They are permanently regenerated from poorly differentiated cells. In order to achieve better healing results, modern medicine relies on so-called stem cell therapy. This therapy method includes all medical therapy procedures that use stem cells as a central component of treatment. The oldest and best known stem cell therapy is leukemia treatment. Stem cells can be isolated from both embryonic and adult tissues. Embryonic stem cells are still omnipotent and thus can differentiate into all tissues. Embryonic stem cells rapidly produce a large quantity of cells that can be inserted into all damaged tissues. However, the high division rate of embryonic stem cells is associated with the risk of tumor diseases. Thus, the study of determination also plays an increased role in tissue proliferation in the context of tumor disease. Determination is equally relevant to the consideration of various malformations or mutations. If the available cells at determination do not cover all developmental programs, then, at worst, the cells of a particular tissue type may not develop. Errors in determination can have correspondingly serious consequences. However, due to the possibility of transdetermination, determination errors can be corrected to a certain extent. If no correction takes place or if the correction proceeds incorrectly, then certain tissues may be overdeveloped while others are underdeveloped.