Familiarization with the information contained in this article will allow the reader to learn about one of the methods of cell division - amitosis. We will find out the features of the flow of this process, consider the differences from other types of division and much more.
What is amitosis
Amitosis is a direct type of cell division. This process occurs due to the usual division of the nucleus into two parts. However, it may miss the spindle formation phase for division. And ligation occurs without condensation of chromatins. Amitosis is a process inherent in animal and plant cells, as well as the simplest organisms.
From history and research
Robert Remak in 1841 gave a description of the process of amitosis for the first time, but the term itself appeared much later. Already in 1882, the histologist and biologist of German origin, W alter Flemming, proposed the modern name for the process itself. Amitosis of a cell in nature is relatively rare, but it can often occur because it is necessary.
Process Features
How does cell division happen? Amitosis most often occurs in cells with reduced mitotic activity. Thus, many cells that should die as a result of old age or pathological changes can delay their death for some time.
Amitosis is a process in which the state of the nucleus during the interphase period retains its morphological features: the nucleolus is clearly visible, as well as its shell, DNA does not replicate, chromatin is protein, DNA and RNA do not spiralize, and the detection of chromosomes in the nucleus eukaryotic cells missing.
There is indirect cell division - mitosis. Amitosis, unlike it, allows the cell to maintain its activity as a functioning element after division. The spindle of division (a structure intended for chromosomal segregation) is not formed during amitosis, however, the nucleus divides anyway, and the consequence of this process is the random distribution of hereditary information. The absence of a cytokinetic process results in the reproduction of cells with two nuclei, which in the future will not be able to enter into a typical cycle of mitosis. Repeated repetition of amitosis can lead to the formation of cells with many nuclei.
Current situation
Amitosis as a concept began to appear in many textbooks back in the 80s of the twentieth century. To date, there are suggestions that all the processes that were previously put under this concept are, in fact, incorrectly interpreted results of studies on poorly prepared micropreparations. Scientists believe that the phenomenon of cell division, accompanied by the destruction of the latter,could lead to the same misunderstood and misinterpreted data. However, some eukaryotic cell division processes cannot be attributed to either mitosis or meiosis. A striking example and confirmation of this is the process of division of the macronucleus (the nucleus of the ciliate cell, large in size), during which the segregation of some sections of the chromosomes occurs, despite the fact that the spindle for division is not formed.
What causes the complication of studying the processes of amitosis? The fact is that this phenomenon is difficult to determine by its morphological features. Such a definition is unreliable. The inability to clearly define the process of amitosis by signs of morphology is based on the fact that not every nuclear constriction is a sign of amitosis itself. And even its dumbbell-shaped form, which is clearly expressed in the nucleus, can only belong to the transitional type. Also, nuclear constrictions may be the result of errors in the phenomenon of previous division by mitosis. Most often, amitosis occurs immediately after endomitosis (a method of doubling the chromosome number without dividing both the cell and its nucleus). Usually, the process of amitosis leads to doubling of the cell nucleus. The repetition of this phenomenon creates a cell with many nuclei. Thus, amitosis creates cells with a chromosome set of a polyploid type.
Conclusion
Summarizing, we can say that amitosis is a process during which the cell divides in a direct type, that is, the nucleus divides into two parts. The process itself is not capable of providing cell division into equal, identical halves. This isalso applies to information about the heredity of the cell.
This process has a number of sharp differences from the staged division by mitosis. The main difference in the processes of amitosis and mitosis is the absence of destruction of the shell of the nucleus and nucleolus during amitosis, as well as the process without the formation of a spindle, which ensures the division of information. The cytotomy does not divide in most cases.
Currently, there are no studies of the modern era that can clearly distinguish amitosis as a form of cell degeneration. The same applies to the perception of amitosis as a method of cell division due to the presence of a very small amount of division of the whole cell body. Therefore, amitosis is perhaps better attributed to the regulatory process that occurs inside the cells.
