Chromosomes are full of human genetic material and their importance cannot be overstated. The couple’s own chromosomes are normal, the embryo chromosomes may also be abnormal. “A dragon gives birth to a phoenix, and a mouse’s child will make a hole”, isn’t it of genetic material? Why is the embryo chromosome abnormal? And see the slow breakdown. 1. Human normal karyotype Human is diploid, generally speaking, the chromosomes in the nucleus of somatic cells are in pairs, there are 23 pairs (i.e. 46), one of which is the sex chromosomes (X and Y), which can determine the sex. The other 22 pairs (i.e., 44) are autosomes, which also have their own Arabic numerical numbers, but are just not written out under normal circumstances. The normal male karyotype is 46, XY. The number 46 means that there are 46 chromosomes in total, and XY means that it contains one X and one Y chromosome. The normal female karyotype is 46, XX. The normal female karyotype includes two X chromosomes. A normal karyotype requires not only a normal number, but also a normal structure. Each of these 46 chromosomes has a unique structure and subdivisions, bands, etc., which can be identified by cellular staining techniques, etc. 2. Sperm and eggs undergo a meiotic process Mature sperm and egg formation undergo a special type of cell division called meiosis, which requires that each pair of these 23 pairs of chromosomes be separated, for example, XY will become an X and a Y, XX will become an X and another X, and the same is true for the 22 pairs of autosomes. The sperm and egg cells thus formed contain only halved sets of chromosomes, which become single from the paired state to form haploid germ cells. This process requires that each of the 23 pairs of chromosomes be dutifully separated, so that in case the pair is not separated, the abnormality occurs from then on. 3. Sperm and egg unite to form a fertilized egg The two haploids, egg and sperm, unite again to allow the single chromosomes to combine again to form a diploid fertilized egg. Normally only one sperm fertilizes the egg, sometimes there is multiple sperm fertilization, which may develop into a gravid abortion. 4. Oogenesis (replication) of the fertilized egg and growth and development of the embryo The fertilized egg, which is full of energy, divides once a day, and this division is called mitosis. The chromosomes first need to be replicated in their entirety, and then they are pulled apart by spindle filaments and divided into daughter cells, so that the number of chromosomes in the daughter cells formed should remain the same. Replication and division of chromosomes can occur with various abnormalities such as chromosome deletions, inversions, insertions, translocations, incomplete divisions, and other problems. The process of embryonic development is accompanied by numerous division processes, and abnormalities may occur. The earlier the abnormality occurs, the greater the impact on embryonic development may be. After reading the above explanation, do you wonder how difficult and amazing it is to conceive a healthy life? It is true, but there is no need to worry too much, because the body has many mechanisms to ensure that the reproductive genetic process is carried out accurately. Chromosomal genetic mutations occur from time to time, and some chromosomal variants may not have much effect, while others can lead to miscarriage, fetal abnormalities, etc. Having children early at an appropriate age, taking care of reproductive health, and practicing healthy habits are measures that can reduce the risk of embryonic abnormalities, while some are random events. If there is a history of embryonic chromosomal abortion, it is recommended to consult a specialist with the report card and relevant information.