 Multiple births, first are contents, uniparous animals, multi-parous animals, monozygotic tyveins and dizygotic tyveins. So, students, first we clear about the, let me clear about multiple births. Multiple births, birth means the birth of a young one or the birth of a baby, or the birth of a baby, or the birth of a baby from the mother's body. So, multiple births means, if one mother is giving birth to one of the young ones, we say it is the multiple births. Births case, if we look at it, some of the animals, they give only birth to one individual. And some of the animals, they give more than one birth. Some of them give birth to one young one, while some give birth to more young ones. So, uniparous animals are those animals which produce only one individual. Uniparous animals are one offspring, one young one, or we can say, one newborn, they are the uniparous animals. According to uniparous animals, most of the animals are uniparous. The common examples we have are the human. Human, at a time, one baby is born in normal conditions. Similarly, many of the cattle, most of the cattle have cows, buffaloes, similarly horses, like other zebra. So, these animals, they normally give birth to the one baby or one young one. So, all these animals which are giving birth to one young one, they are actually the uniparous animals. Multiparous animals means, those animals which give birth to more than one young ones, they give birth to more than one baby. Multiparous animals, they may produce two, three, four, five, six, and so on, individuals who give birth at the same time. We have examples of multiparous animals. They are the cats, rats, mice, dogs. These are examples of multiparous animals. At a time, they give birth to more than one young one. So, multiparous animals, normally the offspring of multiparous animals, they may be males and females. Normally, there are some males and some females. But, some exceptional cases are there. In exceptional cases, we have armadillo. Armadillo, it produces four young ones at the same time. But, some exceptional cases are there. In exceptional cases, we have armadillo. Armadillo, it produces four young ones at the same time. But, all of them will be either males or either females. What will armadillo do? At a time, the female is the one who produces four young ones. And, they are either males or females. But, this is not the rule. In general, males and females are mixed. Some males and some females are produced. So, now we have multiparous animals. Multiparous animals are born at the same time. We get two patterns in more than one birth. Sometimes, there are some individuals who are born from one zygote. One zygote is divided into two. There are two young ones. But, the zygote was one. Those individuals who are produced from single zygote, they are called the monozygotic. These are the twins. Two are born, not more than two. So, in this case, we have monozygotic twins. They are identical twins. Why we are saying identical twins? Because, the young ones who are born from one zygote, they will be strikingly similar. One with striking similarities. And, they will be of same sex. They are either brothers or sisters. This process of two individuals being born from one zygote, is actually as soon as the zygote has started dividing at the initial stage in the mother. Now, the embryo is made. Now, at the two or four cell stage, the cells are divided at the initial stage. Accidentally, this is not the case. So, due to some reason, the embryo has been divided at the initial stage. Now, what will these two parts do? They will create two new young ones. Now, since the zygote has been divided into two embryos, because of which, they will have the same genetic makeup. Because of which, they will have more similarities. Monozygotic twins, if we look at this, normally, there are 33% of them, whose placenta is separated. Whereas, most of them are having the same placenta. What can one placenta do? They are both taking food. Whereas, the amniotic sex, the amniotic sex is a young one who is born from a membrane. Amniotic sex is mostly separated in cases. Monozygotic twins have their own amniotic sex. In some cases, the amniotic sex can be combined. If the amniotic sex is combined, the young ones are very close to each other. In this case, it can be a little dangerous. Why? Because, if they are connected, it can be that they have a common body part, or their body part is fused. As you can see, normally, babies are born or they are all connected or their body parts are connected. The reason for this is that they are both monozygotic twins and during their birth, they are separated in a single place where the amniotic sex is developed. This is a critical situation that is called semi-striwining. Here, we can see that the monozygotic twins initially have one embryo divided in two parts. Now, by dividing it, ultimately, two young ones will be born. The same is the case where one embryo is divided and divided in two parts. We can see that both young ones have separate placenta. In picture B, both young ones are attached to one placenta. So, monozygotic twins can be attached to separate placenta or they are the same placenta. Dizygotic twins are different from monozygotic twins. In dizygotic twins, two eggs are fertilized at the same time. Dizygotic twins mean that mother becomes two eggs at a time. Now, both eggs are fertilized because of which two embryos start to form. Now, since their zygote and embryo are separate, they are not similar. Similarly, when they do not have similarity, the other characters are strikingly similar to each other. Dizygotic twins may be of different sex and may be of same sex. They can be brothers or sisters. They do not have any compulsion and they may have their own amniotic sex. In this diagram, two separate eggs are produced in mother. Each egg has developed separate embryos. Now, after developing embryos, there can be two situations. Both embryos develop their own placenta. There is also a possibility that both embryos develop their own placenta. Both embryos can have different possibilities. But normally, separate placenta and separate embryos. The special thing here is that in Dizygotic twins, two eggs are produced and two separate embryos are produced.