![]() in females, one of the cells is an egg cell while the other three are polar bodies (small cells that do not develop into eggs).in males, these four cells are all sperm cells.Once cytokinesis is complete there are four granddaughter cells, each with half a set of chromosomes (haploid):.This is the last phase of meiosis, however cell division is not complete without another round of cytokinesis.A membrane forms around each set of chromosomes to create two new cell nuclei.The separated chromatids are now individual chromosomes.The sister chromatids are then pulled to opposite poles due to the action of the meiotic spindle.Meiotic spindle fibres at each pole of the cell attach to each of the sister chromatids.The centrioles are now at opposites poles in each of the daughter cells.In each of the two daughter cells the chromosomes (pair of sister chromatids) line up end-to-end along the equator of the cell.The membrane around the nucleus in each daughter cell dissolves away releasing the chromosomes.In each of the two daughter cells the chromosomes condense again into visible X-shaped structures that can be easily seen under a microscope.Now there are two daughter cells, each with 23 chromosomes (23 pairs of chromatids).The single cell then pinches in the middle to form two separate daughter cells each containing a full set of chromosomes within a nucleus.A membrane forms around each set of chromosomes to create two new nuclei.At each pole of the cell a full set of chromosomes gather together.The chromosomes complete their move to the opposite poles of the cell.This is different to what happens in mitosis and meiosis II. In meiosis I the sister chromatids stay together.The pair of chromosomes are then pulled apart by the meiotic spindle, which pulls one chromosome to one pole of the cell and the other chromosome to the opposite pole.The meiotic spindle fibres attach to one chromosome of each pair.The centrioles are now at opposites poles of the cell with the meiotic spindles extending from them.The chromosome pairs line up next to each other along the centre (equator) of the cell.The meiotic spindle, consisting of microtubules and other proteins, extends across the cell between the centrioles.At the end of Prophase I the membrane around the nucleus in the cell dissolves away, releasing the chromosomes.The pairs of chromosomes may then exchange bits of DNA in a process called recombination or crossing over.The chromosomes pair up so that both copies of chromosome 1 are together, both copies of chromosome 2 are together, and so on.Each chromosome is composed of two sister chromatids containing identical genetic information.The copied chromosomes condense into X-shaped structures that can be easily seen under a microscope.During interphase, microtubules extend from these centrosomes. ![]()
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