The brothers Twins they are generated in the same pregnancy and are, therefore, of the same age. Some are very similar, but others are completely different. Those very distinct twins are called dizygotic, while similar twins are called monozygotic.
You dizygotic or fraternal twins they originate from the release of two oocytes at the time of ovulation. In this case, as they are generated from different oocytes and sperm, they have little genetic similarity, only that which occurs between other siblings. For this reason, dizygotic twins are called fraternal.
THE dizygotic twin placenta is separate. However, sometimes, it is not possible to distinguish them easily due to the excessive proximity between them. The proximity can be so great that the differentiation can only be made by observing the region known as the T zone, where it is possible to visualize two amnion and two chorions. Unlike monozygotic twins, dizygotic twins do not always have the same sex.
THE dizygotic twin pregnancy it is very common in infertility treatments. Due to the insertion of several embryos in the woman's uterus, fixation and development of more than one baby can occur.
There are still the monozygotic or univitelline twins, which are mainly characterized by the similarity between individuals. These twins are formed from the same zygote, that is, after the fertilization process. Due to this characteristic, they have the same genetic heritage, being considered, therefore,identical.
These twins must be of the same sex, unlike the dizygotic twins. It is worth noting, however, that some features, such as fingerprints and others phenotypic characteristics are not identical in monozygotic twins, as they are obtained from the interaction of genotype with the middle.
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The formation of monozygotic twins can occur on the first day of fertilization or up to 14 days after. In 30% of cases, this formation begins with the separation of the blastomeres around the third day, when the zygote is still called a morula. In these cases, during development, the formation of individual corium and amnion is observed. In 70% of cases, however, formation begins later and there is the formation of a chorion and two amnions, when division starts until the eighth day of fertilization, and an amnion and a chorion when division starts after that. time course.
Sometimes, problems in the separation of twins lead to the development of individuals united by some part of the body, the so-called Siamese twins.They can be generated by incomplete division or by division with subsequent fusion of some structures. According to the name of the part that is fused, the twins receive a different name, such as thoracopagus (joined by the thorax) and cephalopagus (joined by the head).
In this section you will expand your studies on twins, individuals who arouse a lot of curiosity and have been the subject for the creation of many legends.
Good studies!!!
By Ma. Vanessa dos Santos
Twins are siblings born from the same pregnancy. Some have very similar characteristics and others are completely different. We call twins ___________ those who do not have similar characteristics.
Twins can be of the same sex or not. A group of twins, however, must have the same sex. This is the case for: