What is the Difference between Internal (In Vivo) and External Fertilization (In Vitro)?

The fundamental distinction between external and internal fertilization is that male and female gametes unite outside the female body in external fertilization. However, male and female gametes unite within the female body in internal fertilization.

What is Internal Fertilization (In Vivo)?

The second type of fertilization, known as internal fertilization, occurs inside the female body. To put it another way, it happens when male organisms transmit their gametes to female organisms. This union happens because the male and female gametes mate within the female body. The zygote develops inside female organisms after fertilization until the kid is born. As a result, this method of fertilization protects the female gamete to a large extent.

What is External Fertilization (In Vitro)?

External fertilization, also known as In Vitro Fertilization (IVF), is a form of assistive reproductive technology (ART). It entails extracting eggs from a woman’s ovaries and fertilizing them with sperm. An embryo is a fertilized egg that has been fertilized. The embryo can then be frozen or transplanted to a woman’s uterus for preservation.

IVF can utilize your eggs and your partner’s sperm, your eggs and donor sperm, donor eggs and your partner’s sperm, donor eggs and donor sperm, or donated embryos, depending on your scenario. Further, your doctor can also use a surrogate, or gestational carrier, to implant embryos.

Difference between Internal & External Fertilization

Internal Fertilization (In Vivo)

The sperm and egg are fused inside the female body during this method of fertilization. During this process, the male releases his sperm into the female’s vaginal canal, where the embryo develops within the woman’s uterus.

A single egg from a single egg follicle is all that’s needed for Internal Fertilization to make an embryo. As a result, internal fertilization requires just a small number of gametes.

Internal fertilization has a greater survival percentage for embryos because the fertilized egg is contained inside the uterus’s protective layers.

Except in rare twins, triplets, or more, most women who give birth naturally by in vitro fertilization have just one child. Internal fertilization has a lower risk of miscarriage than external fertilization of giving birth to defective children.

External Fertilization (In Vitro)

The sperm and egg are fused in an IVF laboratory during external fertilization, which is a procedure. Embryos and sperm must be removed to carry out this form of fertilization.

To ensure the viability of the egg, fertility medicines are used. Multiple egg follicles are grown and matured in both ovaries of the lady. External fertilization causes the use of a high number of gametes.

The transvaginal aspiration procedure removes the egg from the uterus after being observed via ultrasonography. The semen sample of the guy is also used to gather the needed quantity of sperm. Then, embryologists are trained to insert a single sperm into each egg in an IVF facility using the most advanced technology.

Incubators are needed to keep the eggs and sperm in the right conditions for fertilization. The embryos are delivered to the uterus five days after their extraction.

These embryos are put into the uterus as one or more high-quality embryos since the survival rate is lower than internal fertilization. In addition, external fertilization raises the likelihood of multiple pregnancies since numerous embryos are transplanted.

In Vivo

In Vitro

“In Life” meaning the study takes place in a aliving organism

“The study takes place in a test tube” means that it takes place in a glass container.

More expensive than in vitro

High Cost

More precise

Less precise

Least used method

Most commonly used method

Read Also – How Many Injections for IVF Treatment?

Factors to consider

Listed below are the factors to consider:

  • Occurrence of external and internal fertilization
  • Need for water
  • Amount of wastage of gametes
  • Number of gametes produced
  • The survival rate of embryos
  • Parental care

Advantages and Disadvantages of In Vitro and In Vivo

Advantages of in Vitro Method

As a supply of feeder cells while antibody creation is underway, in vitro approaches may limit the utilization of mice during the antibody-production stage.

Using in vitro procedures eliminates the requirement for IACUC approval of animal experiments.

Disadvantages of in Vitro Methods

Some hybridomas cannot thrive in culture, or they are lost in being propagated.

Using FBS in vitro procedures restricts the use of particular antibodies. In vitro procedures for manufacturing mAbs often need FBS, which raises animal-welfare concerns.

Advantages of Mouse Ascites Method

High levels of mAb may be obtained using the mouse ascites technique with no further concentration steps, which can denature the antibody and reduce its efficacy.

Mouse ascites fluid has the mAb at a high concentration, which prevents impurities from interfering with in vitro batch culture fluid.

Disadvantages of Mouse Ascites Method

The purification of mAbs generated by in vivo techniques may need the removal of many mouse proteins and other impurities.

If immune-deficient animals in a barrier facility are required, the mouse ascites approach might be costly to carry out successfully.


Internal fertilization takes place within the female body as opposed to external fertilization. For fertilization, exterior and internal methods are quite different. The gametes of male and female organisms are released into the environment during external fertilization. As for internal fertilization, the male organism implants male gametes into the female organism.

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