An ultrasound performed on a women, shows twin pregnancy. Which of the following is a feature of dizygotic twins?
**Core Concept**
Dizygotic twins are formed when two separate eggs are fertilized by two different sperm, resulting in two genetically distinct fetuses. This process is similar to single pregnancies, with each fetus developing independently.
**Why the Correct Answer is Right**
Dizygotic twins have distinct genetic material, meaning they are no more alike than any two siblings from the same family. Since they develop from separate eggs, each twin has its own placenta and amniotic sac. This characteristic is a key feature of dizygotic twins.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because monozygotic twins, not dizygotic twins, have identical genetic material.
* **Option B:** This option is incorrect because dizygotic twins do not share the same amniotic sac, but rather have separate amniotic sacs for each fetus.
* **Option C:** This option is incorrect because while dizygotic twins may have different sex, this is not a defining feature of dizygotic twins, as some dizygotic twins can be the same sex.
**Clinical Pearl / High-Yield Fact**
Dizygotic twins are more common than monozygotic twins and are often the result of assisted reproductive technologies (ART).
**Correct Answer:** B. Dizygotic twins have distinct genetic material, separate placentas, and separate amniotic sacs.