What Is a Polar Body?
Polar body refers to one large haploid egg cell and two to three small cells. When the first mature (meiotic) division occurs, a large secondary oocyte and a small first polar body are formed; during the second mature division, a small second polar body is also produced. The first polar body is usually split into two polar bodies. The initially formed polar body is located in the animal pole of the egg. The polar body has very little cytoplasm and lacks nutrients. It quickly degenerates and disappears, thereby ensuring the storage of a large amount of cytoplasm in the egg cell for the needs of early embryo development.
Polar body
discuss
- Chinese name
- Polar body
- Foreign name
- polarbody
- Types of
- Small cells
- the reason
- Female germ cells mature and divide
- Polar body refers to one large haploid egg cell and two to three small cells. When the first mature (meiotic) division occurs, a large secondary oocyte and a small first polar body are formed; during the second mature division, a small second polar body is also produced. The first polar body is usually split into two polar bodies. The initially formed polar body is located in the animal pole of the egg. The polar body has very little cytoplasm and lacks nutrients. It quickly degenerates and disappears, thereby ensuring the storage of a large amount of cytoplasm in the egg cell for the needs of early embryo development.
- The mammalian second mature division is completed after the sperm enters the egg cell. After the sperm enters the egg, the cortical particles of the egg are released, so there is no cortical particle in the formed second polar body.
- Why form a polar body
- Uneven division results in the production of cells of different sizes. Here, cells that can eventually develop into egg cells have large volumes and large cytoplasm, and cells with small cell volumes and small cytoplasm are called polar bodies. Animal poles located in eggs. Here, the reverse method can be used. If the cells are divided equally, the cytoplasm content and nutrient content obtained by the two cells should be the same, that is, there is no difference in volume between the two cells, and they each have the ability to develop into egg cells. This is not conducive to subsequent fertilized egg development, because nutrients should be preferentially supplied for fertilized egg development, and organisms will choose a way that is conducive to their own survival during evolution.