The Greek word zygoûn (which translates as “join”) led to zygōtós (“United”), which in turn reached our language What zygote or zygote. The zygote is called cell resulting from the fusion of the female gamete with the male gamete in the process of sexual reproduction that plants and animals develop.
From the term that concerns us, other equally important ones have emerged, such as the following:
-Heterozygous, which is used to refer to that cell that is formed from the union of two gametes that have different constitution.
-Homozygous, which is used to refer to a cell that is created from the union of two gametes of the same constitution.
Also called egg, the zygote arises when the spermatozoon joins the Ovum. When their respective nuclei fuse, the nucleus of the zygote emerges, which has two complete sets of chromosomes (one of each gamete). Organelles and cytoplasm, meanwhile, come from the Ovum.
Once the zygote is formed, its segmentation, which includes successive mitoses to give rise to blastomeres (embryonic cells), which in turn give rise to the morula and then to blastula. In the continuity of embryonic development, the blastula becomes gastrula and then in neurula. In this sequence, the zygote goes from the fallopian tube to him uterus.
The various phases of segmentation are known as blastulation, gastrulation Y organogenesis. When embryonic development concludes, the zygote is renamed fetus.
According to the location and level of yolk (substances that allow nutrition embryo), zygotes can be classified into centrolecitic (with great abundance of yolk); tellecytic; mesolecytic or heterolecitic; Y oligolecitic or isolecitic (with little yolk).
It is important to bear in mind that it is possible to differentiate two large poles: the animal or germinative pole, which houses the core and metabolic activity, and vegetative pole where the aforementioned yolk accumulates.
It must be stated that it is very common to confuse the terms zygote, embryo and fetus. And it is that they are used on a regular basis to refer to the future baby on the way in a pregnancy. However, it must be clear that they mention it but in the different phases of what its prenatal development would be:
-Zygote is the cell that arises when the sperm and ovum fuse their nuclei during fertilization. It usually has 46 chromosomes and its size is identical to that of the mentioned ovum.
-Embryo is the one that occurs from the first day after fertilization until the eighth week of gestation.
-Fetus. In this case, we can state that the end of the embryonic stage and the beginning of the fetal stage are considered to take place from week 8 of pregnancy. At this time, the embryo is considered to be a fetus. This will make it grow as its vital organs develop and it will acquire the appearance of a baby until it is born, which usually happens between 38 and 40 weeks of pregnancy, as a rule.