The meiotic division stages actually have similarities to the steps in mitosis. Meiosis itself is often known as reduction cleavage.
This meiotic division comes from the word meioun which means reduction. Meanwhile, the history of the discovery of meiosis in 1883 was explained by Edouard van Beneden.
At that time he made observations on worm eggs Ascaris sp. which has half the chromosomes of the number of chromosomes in the automatic cell.
Understanding and Stages of Meiosis Division
The definition of meiotic division is a division process that has reducing properties. The goal is to produce gametes.
Another name for this meiotic division is reduction division which is caused by a reduction in the number of diploid or chromosomes 2n to be haploid or n.
Meiotic division is very important for an organism whose reproduction process is sexual, namely in the process of gametogenesis.
Meiosis is divided into two nuclear divisions or karyokinesis. The first is meiosis I and meiosis II. The difference between the two is in a crossover and multiplication of chromosomes.
In meiosis I there is a reduction or reduction in the number of chromosomes. While in meiosis II the process is the same as mitotic division. The following are the stages of meiotic division that you need to know.
In meiosis I there are 4 stages. prophase I, metaphase I, anaphase I, and telophase I. Initially, meiosis I, the nucleus undergoes enlargement and can absorb water from the cytoplasm by the nucleus which reaches 3 times.
At this stage, the nuclear membrane will begin to break down and become fragments, then form the cleavage spindle.
Then the chromatin thread becomes dense and the chromosomes then the homologous chromosomes are paired. Then there will be an exchange of the appropriate DNA molecule segments.
Furthermore, the meiosis I division stage is metaphase I. At this stage the homologous chromosomes are neatly arranged on the equator.
The arrangement is above the metaphase plate. Then the spindle fibers will stick in two centromeres in each homologous chromosome.
In this stage of anaphase I, the homologous chromosomes separate towards the opposite pole. This is caused by the pull of the bobbin thread. In addition, at this anaphase I stage, the chromosome reduction process also occurs.
This is where the membrane starts to form again. This process is often called the cytokinesis process. Cytokinesis is a condition when the cytoplasm of eukaryotic cells divides into two daughter cells.
The stages of meiosis II division are similar to those that occur in mitosis. What are the stages?
In the prophase II stage, the centrosome will divide into two centrioles whose movements are towards the opposite cell poles. In addition, the chromatids will also move into the cleavage plane.
At this stage, the chromosomes are neatly aligned in the cleavage plane or at the equator. Then from there various spindle threads are arranged, one end attached to the centromere. Meanwhile, the other end will go in the opposite direction.
In this stage of anaphase II, the chromatids will separate and also move to the opposite pole. The chromatids that have separated means that they have officially become chromosomes.
If you know, telophase II is the last meiotic division stage of the whole process that occurs. In this stage, the nucleus has begun to form.
In addition, this part of the membrane has also begun to appear. The spindle threads are also lost and the cytokinesis process will occur again. Normally, in this last process, four daughter cells will be formed.
Meiosis Cleavage Characteristics
You can see various kinds of features of meiotic division such as the occurrence of sex cells. Has 4 daughter cells. The number of chromosomes they have is half that of the parent.
The process of splitting twice. It takes longer if compared to mitosis splitting.
In addition, the meiotic division stage has a more complex process. Therefore, in accordance with the objectives of meiotic division, namely to produce gametes, increase the genetic variability of gametes, and halve the chromosomes. (R10 / HR Online)