The Internal fertilization Is that which occurs when the female and male gametes are united within the body of the recipient and future mother. That is, when the process in which the sperm fertilizes the ovum occurs within the female body.
The purpose of the existence of living beings is reproduction. In order to keep a species alive, it is necessary that the species reproduce because otherwise, it is extinguished.
Pigeons mating.
Internal fertilization is the most used among animals. Fertilization or fertilization is the first step for any new life.
Differences between internal and external fertilization
Fertilization is only given in the Sexual reproduction . Organisms that have asexual reproduction methods do not require fertilization and no fertilization in order to be able to procreate.
Certainly the most frequent type of fertilization is the internal one. This is present in many species, however this type of fertilization is not exclusive; Many other beings depend on external fertilization to reproduce.
Internal Fertilization
It is given in humans, mammals, reptiles, some insects and many birds. This type of fertilization mostly ensures the growth of the fetus, inside the body of the mother.
Because the union of gametes occurs within the female, the fetus will grow and develop there until ready to be born.
This method is especially used in terrestrial species, since internal fertilization is the only one that can occur in non-aquatic environments.
External fertilization
It is only given in aquatic environments where sperm can travel to the egg. The reason behind this condition is simple; The spermatozoa being expelled in a place without water, would have no way to reach the egg to fertilize it.
This fertilization occurs in most fish and also in amphibians. In this type of fertilization, the ovum of the female is expelled to the outside and the male expels the sperm.
This helps multiple reproduction, because not being inside the mother, there can be thousands of eggs to be fertilized. However, fertilization is not always accurate and this means that several eggs placed by the female end up being food for other fish or sink and fail to be fertilized.
The probability of survival of the offspring impregnated in this way are smaller than those whose fecundation is internal.
Types of gestation and birth derived from internal fertilization
Depending on the species and the environment in which it develops, the way to bring their offspring to the world will be different.
The internal fertilization has 3 types of gestation and birth: the viviparous, the ovípara and the Ovoviviparous .
Ovigous and ovoviviparous gestation in most cases produces many more calves than viviparous gestation. In humans the most common is to have only one baby, the dogs on the other hand can have from 6 to 8. However, a bird or a reptile can give dozens of offspring or more than dozens.
The great similarity of all species with internal fertilization is that although certain species take care of their offspring longer after birth, they all take care of them for a time to prepare them for their environment.
Life span
It is the one that occurs in the human species and all mammals. Here, the female will carry her embryo inside and will provide everything necessary for the correct development and growth of the baby until birth.
The duration of pregnancy may vary. Human females have 9 months of gestation whereas elephant females should be about 22 months old.
Oviparity
This differs from the other two types because although fertilization occurs within the female, the development of the embryo does not.
Birds are the best example. The male fertilizes the female internally and it will deposit eggs, the young will develop inside the egg.
Unlike fish, birds take care of their eggs and give them warmth so that their offspring develop in a good way.
Ovoviviparity
This could be defined as the combination of the two types above. The offspring are found in eggs, however, all of these are found inside the mother.
Vipers are ovoviviparous. They keep the eggs inside their body and only expel them when the offspring are fully developed.
Can humans have another type of fertilization?
In Vitro Fertilization or Artificial Insemination are methods of reproduction given outside the scheme of"natural sexual reproduction". These methods have been developed in search of solving the problems of fertility derived by multiple causes.
There are many people in the world who wish to be biological parents and for many reasons they can not be. Technology has made great strides in this area by developing fertility treatments and different methods of fertilization.
In vitro fertilization is a curious case about human fertilization. Human fertilization is characterized by being internal; The male gamete meets the female within the mother. However, in vitro fertilization is not performed within the mother.
The eggs are extracted together with the semen sample and the union of both gametes is done in a laboratory. After this process, the fertilized egg returns inside the mother.
Although the gestation of a baby that has been created in this way is given inside the woman's womb, fertilization is not done within her.
Therefore, humans through science can have an external fertilization and thus break the rule of fertilization in humans.
References
- "External and Internal Fertilization"Recovered on July 09, 2017 from boundless.com
- Cheprasov, A."Internal & External Fertilization in the Animal Kingdom"Recovered on July 09, 2017 from study.com
- (2012)"Difference Between External and Internal Fertilization"Recovered on July 10, 2017 from differencebetween.com
- (2012)"Advantages & Disadvantages of Internal and External Reproduction"Retrieved on July 10, 2017 from floydbiology.blogspot.com
- "Internal fertilization"Recovered on July 10, 2017 from en.wikipedia.org
- "External fertilization"Retrieved on July 10, 2017 from en.wikipedia.org
- Advanced Fertility Center of Chicago"IVF - In Vitro Fertilization Procedures Step by Step"Retrieved on July 10, 2017 from advancedfertility.com.