Biology

Types of fertilization

What is fertilization?

The fertilization is the process by which two gametes come together resulting in the formation of a new individual who combines the genome of their players . The generation of this new individual concludes the reproductive stage .

Classification of fertilization

There are different types of fertilization, and they are the following:

-Internal fertilization: It is the simplest process, and less diffuse. The sperm pass the body of the female through the coupler body in the male coupling process . There is also a variant in which the female takes the sperm previously released by the server. Internal fertilization, in short, occurs when two gametes or sex cells unite inside the mother’s body, either in the uterus or in the womb.

In oviparous the fertilization is internal and the development of the embryos takes place inside an egg. In ovovivipars, fertilization is also internal, although embryonic development is incomplete, since fetuses complete their formation externally to the maternal body. The viviparous ones, for their part, respect internal fertilization, but the development of the embryos occurs in the mother’s body.

-External fertilization: It is characteristic of aquatic animals, and is distinguished by the fact that the unfertilized ovules and sperm are released into the water, where the encounter takes place . It varies depending on the invertebrate to multiply, although in principle, in fish, reproduction is carried out by the female who leaves the ovules in the water and they are fertilized by the male. The eggs remain floating in the water , although some can also sink to the bottom and settle, but most do not reach the final stage as they serve as food for other fish. Only sharks and hammerhead fish have internal fertilization, that is, through the penetration of the male into the body of the female.

Regarding amphibians, they are oviparous and reproduce through external fertilization. The males are in charge of serving the females and they release the ovules into the water, so that the male deposits his sperm on them and fertilization takes place. The eggs do not have a shell, and the young undergo metamorphosis, going from an initial appearance of tadpoles – which do not have legs – to the adult physiognomy in which they acquire all four limbs.

-In vitro fertilization: It is that technique by which the fertilization of the oocytes using sperm is carried out externally to the mother’s body . The in vitro process is the most effective treatment known to date to overcome cases of infertility, while other methods and elements of assisted reproduction did not achieve the necessary success rate, nor did they ensure the safety of the embryo’s health.

The process of in vitro fertilization itself is quite simple, it consists of controlling the mother’s ovulation and extracting one or two oocytes from the ovaries to fertilize them with sperm in a liquid medium. Once this first stage is finished, the fertilized oocyte is admitted again to the mother’s womb.

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