Sister chromatids are separated during meiosis in the anaphase stage of both meiosis I and meiosis II.

Meiosis is a specialized type of cell division that results in four daughter cells, each containing half the number of chromosomes of the original parent cell. The separation of sister chromatids during the anaphase stage is a critical step in this process, as it contributes to the formation of genetically diverse sex cells, or gametes.

In meiosis I, homologous chromosomes, each consisting of two sister chromatids, align at the cell’s equator during metaphase I. During anaphase I, these homologous chromosomes are pulled apart by spindle fibers towards opposite poles of the cell. Importantly, at this stage, the sister chromatids remain attached to each other. Following this, the cell undergoes cytokinesis, resulting in two daughter cells, each containing a pair of sister chromatids for every chromosome.

In meiosis II, the two daughter cells from meiosis I undergo a second round of cell division. During metaphase II, the sister chromatids align again at the cell’s equator. In anaphase II, the sister chromatids are finally separated and pulled to opposite poles by the spindle fibers. After cytokinesis, this division results in four haploid daughter cells, each with a single copy of each chromosome.

The separation of sister chromatids is a fundamental process in meiosis, ensuring that each resulting gamete contains a unique set of genetic material. This genetic diversity is essential for sexual reproduction, as it facilitates the combination of different gene sets from two parents in their offspring. The process is meticulously regulated by the cell to guarantee that each daughter cell receives an equal and accurate distribution of chromosomes. Errors during this process can lead to genetic disorders, such as Down syndrome, which results from an extra copy of chromosome $21$.