Meiosis consists of two consecutive rounds of cell division, known as meiosis I and meiosis II, each comprising four distinct phases: Prophase, Metaphase, Anaphase, and Telophase.

In total, the phases of meiosis I include Prophase I, Metaphase I, Anaphase I, and Telophase I, while meiosis II encompasses Prophase II, Metaphase II, Anaphase II, and Telophase II.

This specialized form of cell division results in four daughter cells, each containing half the number of chromosomes compared to the original parent cell. The process is crucial for sexual reproduction and contributes to genetic diversity through two successive divisions.

Meiosis I

1. Prophase I: During this initial phase, chromosomes condense and become visible under the microscope. The nuclear envelope disintegrates, and spindle fibers begin to form. A significant event during Prophase I is the pairing of homologous chromosomes, which engage in a process known as crossing over. This exchange of genetic material is vital for increasing genetic variation among offspring.

2. Metaphase I: In this phase, the paired homologous chromosomes align along the equatorial plane of the cell. Unlike mitosis, where individual chromosomes align, meiosis I features paired chromosomes, showcasing its unique nature.

3. Anaphase I: Following Metaphase I, the homologous chromosomes are pulled apart and migrate towards opposite poles of the cell. It is important to note that the sister chromatids remain attached at their centromeres during this stage.

4. Telophase I: The final phase of meiosis I sees the chromosomes reaching the poles of the cell, where the nuclear envelope reforms around each set of chromosomes. This is followed by cytokinesis, leading to the division of the cell into two haploid daughter cells.

Meiosis II

Meiosis II closely resembles a typical mitotic division:

1. Prophase II: The second round begins with the breakdown of the nuclear envelope once more and the reformation of the spindle fibers.

2. Metaphase II: The chromosomes, now unpaired, align at the cell’s equator.

3. Anaphase II: This phase involves the separation of sister chromatids, which are pulled to opposite poles of the cell.

4. Telophase II: Finally, the chromosomes arrive at the poles, the nuclear envelope reforms, and cytokinesis occurs, resulting in four haploid daughter cells.

Summary

In summary, both meiosis I and meiosis II consist of four phases: Prophase, Metaphase, Anaphase, and Telophase. The primary distinction between the two is that meiosis I is characterized by the separation of homologous chromosomes, whereas meiosis II involves the separation of sister chromatids. This intricate process is essential for producing genetic diversity, which is a cornerstone of sexual reproduction.