Meiosis and Prophase – II

Download PDF of This Page (Size: 320K)

Meiosis – II has the four sub-stages; Prophase II, Metaphase II, Anaphase II and Telophase II.

Prophase – II

The chromosomes split into chromatids in both the haploid nuclei and cells formed after meiosis-I. Centrioles move to the cell poles. Nucleolus and nuclear membrane disappear. Spindle fibres are formed at each pole.

Image showing Prophase II.

Image Showing Prophase II.

Image showing Prophase II.

Metaphase – II

Chromosomes move to the centre of the equatorial plane. They get attached to spindle fibres centromere. Formation of spindle apparatus is completed and this is very short phase of meiosis II.

Image showing Metaphase II.

Image Showing Metaphase II.

Image showing Metaphase II.

Anaphase – II

The two sister chromosomes of each pair start to move towards the opposite poles of the spindle due to contraction of the spindle fibres. They are being drawn towards the opposite poles by their centromeres. The centromere in each chromosome divides.

Image showing Anaphase II.

Image Showing Anaphase II.

Image showing Anaphase II.

Telophase – II

The chromosomes begin to uncoil and become thin. Nuclear membrane forms around the chromatids at each pole, once the membrane is formed; each chromatid is then called a chromosome. Cytokinesis follows and four haploid daughter cells are formed and thus the meiotic division is completed.

Image showing Telophase II.

Image Showing Telophase II.

Image showing Telophase II.

Cytokinesis:

Cytokinesis may occur in two successive stages, once after meiosis-I and then after meiosis-II and in some instances it occurs only after meiosis-II.

Significance of Meiosis:

Meiosis helps to maintain the chromosome number constant in each plant and animal species. In meiosis four haploid daughter cells are formed from a single diploid cell. This is very important in sexual reproduction during the formation of gametes.

Meiosis forms spores (n) from the spore mother cells (2n) and thus maintains the alternation of generations in organisms.

The occurrence of crossing over results in the recombination of genes. The recombination of genes results in genetic variation. The genetic variations form raw materials for evolution.

All the four chromatids of a homologous pair of chromosomes segregate and go over separately to four different daughter cells. This leads to variation in the daughter cells genetically.

Sign In