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 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 core into two parts. However, it may miss the spindle formation phase for division. And ligation occurs without the condensation of chromatins. Amitosis is a process characteristic of animal and plant cells, as well as simple organisms.
From history and research
In 1841, Robert Remak described the amitosis process for the first time, but the term itself arose much later. Already in 1882, a histologist and biologist of German origin Walter Fleming proposed a modern name for the process itself. Cell amitosis in nature is a relatively rare occurrence, but often it can occur, as it is necessary.
Process features
How is cell division? Amitosis most often occurs in cells with reduced mitotic activity. Thus, many cells that must 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 characteristics: the nucleolus is clearly visible, like its shell, DNA does not replicate, chromatin is protein, DNA and RNA do not spiralize, and chromosome detection in the nucleus of eukaryotic cells is absent.
There is indirect cell division - mitosis. Amitosis, in contrast to it, allows the cell after division to maintain its activity as a functioning element. The spindle of division (a structure intended for chromosomal segregation) is not formed during amitosis, however, the nucleus is still divided, and the result of this process is a random distribution of hereditary information. The absence of a cytokinetic process as a result leads to the reproduction of cells with two nuclei, which in the future will not be able to enter a typical mitosis cycle. Repeated repetition of amitosis can lead to the formation of cells with many nuclei.
Current situation
Amitosis as a concept began to arise in many textbooks back in the 80s of the twentieth century. Today, there are assumptions that all processes that were previously placed under this concept, in fact, are incorrectly interpreted research results 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 interpreted data. However, some processes of division of eukaryotic cells cannot be attributed either to mitosis or to meiosis. A vivid example and confirmation of this is the process of division of the macronucleus (the nucleus of the ciliates, large in size), during which 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 characteristics. Such a definition is unreliable. The inability to clearly identify amitosis by morphological signs 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 relate only to the transitional type. Also, constrictions of the nucleus may be the result of errors in the phenomenon of the previous division of mitosis. Most often, amitosis occurs immediately after endomitosis (a way of doubling the chromosome number without dividing both the cell and its nucleus). Usually, the amitosis process leads to a doubling of the cell nucleus. A repetition of this phenomenon creates a cell with many nuclei. Thus, amitosis creates cells with a chromosome set of polyploid type.
Conclusion
Summing up, we can say that amitosis is a process during which a cell divides into a direct type, that is, the nucleus is divided into two parts. The process itself is not able to provide cell division into equal, identical halves. This also applies to information about the heredity of the cell.
This process has a number of sharp differences from phased 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 provides information sharing. Cytotomy in most cases is not divided.
There are currently no studies of the modern era that could 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 may be better attributed to the regulatory process occurring inside the cells.