Fertilization is the process of commencing the formation of a new organism of its type by the union of male and female gametes. The zygote is formed when male sperm and female egg combine. This structure contains critical genetic information from both the mother and father.

Internal Fertilization

Internal fertilization refers to the combination of an egg and a sperm cell in sexual reproduction within the female body. Internal fertilization, as opposed to external fertilization, gives the female more control over reproduction. Internal fertilization is the procedure of fertilization that happens within an individual’s body. It is usually found in inland animals. There must be a means for introducing male sperms into the female reproductive tract for internal fertilization to occur. The sperms are transferred in various ways by different animals.

Internal fertilization can create offspring in three ways – Viviparity, Ovoviviparity, and Ovoviviparity

Oviparity

The fertilized eggs are placed outside the mother’s body. The yolk provides nutrition to the egg. Fish, amphibian species, species of reptiles, and all kinds of birds, for example, are all oviparous.

Ovoviviparity

The fertilized eggs are maintained in the female while the embryo is fed by the yolk. The young are completely formed when they hatch. This is experienced in some bony fish species, sharks, reptiles, and snakes, among others.

Viviparity

The child grows within the mother and takes nutrients from the placenta. The majority of mammals, as well as a few reptiles, are viviparous. 

Advantages & Disadvantages Of Internal Fertilization

Advantages

• As a result of being fed by a parent, you have a high probability of surviving.
• The rate of successful fertilization is high.
• Surviving in tough situations has a high chance of success. 

Disadvantages

• There are several offspring generated.
• Finding a partner necessitates less effort.
• There is less competition among parents and their kids.

External Fertilization

External fertilization is a type of reproduction in which the sperm of a male creature fertilizes the egg of a female organism outside the female’s body. Internal fertilization, in which sperm are delivered by insemination and subsequently mix with an egg within the body of a female organism, is in contrast. 

Features Of External Fertilization 

• Fertilization has an extremely low success rate.
• In contrast to internal fertilization, the male and female must create a significant quantity of gametes to assure reproductive success.
• External fertilization must begin in the presence of a body of water. Onshore, the sperms would perish.
• Most animals are at a reproductive disadvantage because the majority of gametes perish without being fertilized.
• External fertilization, on the other hand, is a straightforward reproductive method that does not need the use of hormones. 

Advantages & Disadvantages Of External Fertilization

Advantages

• Finding a partner necessitates a significant amount of effort.
• The female counterpart contributes the majority of the time.
• There were few offspring generated.

Disadvantages

• Because they are readily preyed upon and without parental care, their chances of survival are reduced.
• The majority of the children are unfertilized and die before reaching adulthood.
• Only in a moist and humid atmosphere can you survive.

Human Fertilization Through External Fertilization

External fertilization occurs in humans as well, although it is not normal. Several females have obstructed oviducts. The sperms are unable to reach the eggs, and the female is unable to conceive. In this case, the physicians gather newly released eggs and sperms and preserve them together for many hours in order to perform in-vitro fertilization. After fertilization, the zygote is moved to the female’s uterus for roughly a week, and the developmental process begins within the mother’s womb.

Difference Between Internal And External Fertilization

Internal Fertilization

• Fusion of gametes occurs inside the female body.
• Lesser gametes are discharged and placed into the female’s body.
• Male gametes are the only ones that are released into the female vaginal canal.
• Inside the female body, additional development occurs.

External Fertilization

• Gamete union in an outer environment like Water Bodies.
• Multiple gametes are released into the environment. 
• Both male and female gametes are released into the atmosphere.
• Outside of the female body, additional development occurs. 

Conclusion 

We discussed internal fertilization, external fertilization, and other related topics through the study material notes on the difference between internal and external fertilization. 

Internal fertilization occurs when the sperm fertilizes the egg inside the female; there are three methods: oviparity, viviparity, and viviparity. External fertilization is a type of reproduction in which the sperm of a male creature fertilizes the egg of a female organism outside the female’s body. Internal fertilization, in which sperm are delivered by insemination and subsequently mix with an egg within the body of a female organism, is in contrast.

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