Amniocentesis is based on

Options

A. Analysis of chemical composition of fluids of pregnant woman
B. Withdrawal of allantoic fluid from pregnant women
C. An in vitro diagnosis
D. Culturing of cells and study of metaphase chromosomes from amniotic fluid to identify chromosomal abnormality

Answer

**Step-by-Step Solution:**

1. **Understanding Amniocentesis**: Amniocentesis is a medical procedure used during pregnancy to obtain amniotic fluid, which surrounds the fetus. This fluid contains cells shed by the fetus and can provide valuable information about the baby's health.

2. **Location of Amniotic Fluid**: The amniotic fluid is found in the amniotic sac, which is a protective layer surrounding the embryo and is part of the placental structure.

3. **Purpose of Amniocentesis**: The primary purpose of amniocentesis is to test for chromosomal abnormalities and genetic disorders in the fetus. By analyzing the cells in the amniotic fluid, healthcare providers can identify potential genetic issues.

4. **Evaluating Options**:
- The first option refers to the analysis of the chemical composition of the fluid, which is not the main focus of amniocentesis.
- The second option mentions the withdrawal of allantoic fluid, which is incorrect as allantoic fluid is different from amniotic fluid.
- The third option suggests that amniocentesis is an in vitro diagnosis, which is misleading since it involves sampling fluid from within the body.
- The fourth option discusses culturing cells and studying metaphase chromosomes from the amniotic fluid to identify chromosomal abnormalities, which aligns with the purpose of amniocentesis.

5. **Conclusion**: Based on the analysis, the correct basis of amniocentesis is the culturing of cells and studying the metaphase chromosomes from the amniotic fluid to identify chromosomal abnormalities.

**Final Answer**: Amniocentesis is based on the culturing of cells and studying the metaphase chromosomes from amniotic fluid to identify chromosomal abnormalities.

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