In which of the assisted reproductive technology the embryo is formed by in vivo fertilization?

Options

A. ZIFT
B. IVF-ET
C. IUT
D. GIFT

Answer

To determine which assisted reproductive technology (ART) involves in vivo fertilization, we need to analyze the options provided. In vivo fertilization refers to fertilization that occurs inside the female body. Let's evaluate each option step by step:

### Step 1: Understand the term "in vivo fertilization"
- In vivo fertilization means that the fertilization of the egg by the sperm occurs within the female's body, specifically in the fallopian tubes.

### Step 2: Analyze the first option - GIFT (Gamete Intrafallopian Transfer)
- GIFT involves transferring both sperm and unfertilized oocytes (eggs) directly into the fallopian tubes.
- Since fertilization occurs inside the female body after the gametes are placed in the fallopian tubes, this is an example of in vivo fertilization.

### Step 3: Analyze the second option - IVF-ET (In Vitro Fertilization - Embryo Transfer)
- IVF involves fertilizing the egg with sperm outside the body (in vitro) and then transferring the resulting embryo into the uterus.
- Since fertilization occurs outside the female body, this option does not represent in vivo fertilization.

### Step 4: Analyze the third option - IUT (Intrauterine Transfer)
- IUT involves transferring an already fertilized embryo (which has developed to at least the 8-cell stage) into the uterus.
- As the fertilization has already occurred outside the body before the transfer, this is not an example of in vivo fertilization.

### Step 5: Confirm the correct answer
- After evaluating all options, GIFT is the only method where fertilization occurs inside the female body, making it the correct answer.

### Final Answer:
**The embryo is formed by in vivo fertilization in GIFT (Gamete Intrafallopian Transfer).**

---