Ch. 29 Heredity

Marieb, Hoehn11th EditionHuman Anatomy & PhysiologyISBN: 9780136874034Not the one you use?Change textbook
Chapter 29, Problem 8
Compare and contrast amniocentesis and chorionic villus sampling as to the time at which they can be performed and the techniques used to obtain information on the fetus’s genetic status.
Verified step by step guidance1
Step 1: Define amniocentesis and chorionic villus sampling (CVS) to establish a clear understanding of each procedure. Amniocentesis involves sampling the amniotic fluid surrounding the fetus, while CVS involves sampling cells from the chorionic villi of the placenta.
Step 2: Identify the typical time frame during pregnancy when each procedure is performed. Amniocentesis is usually done between the 15th and 20th weeks of gestation, whereas CVS is performed earlier, typically between the 10th and 13th weeks.
Step 3: Describe the techniques used to obtain fetal genetic material. Amniocentesis uses a needle inserted through the mother's abdominal wall into the amniotic sac to withdraw amniotic fluid containing fetal cells. CVS involves inserting a catheter or needle either through the cervix or abdomen to collect chorionic villi tissue.
Step 4: Explain the type of genetic information obtained from each procedure. Both provide fetal cells that can be cultured and analyzed for chromosomal abnormalities and genetic disorders, but CVS provides earlier results due to earlier sampling.
Step 5: Summarize the advantages and limitations of each method, including timing, risk factors, and diagnostic capabilities, to highlight their comparative uses in prenatal genetic diagnosis.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Amniocentesis
Amniocentesis is a prenatal diagnostic procedure performed typically between the 15th and 20th weeks of pregnancy. It involves extracting a small amount of amniotic fluid using a needle inserted through the abdomen, which contains fetal cells used for genetic analysis. This technique helps detect chromosomal abnormalities and genetic disorders.
Chorionic Villus Sampling (CVS)
Chorionic Villus Sampling is an earlier prenatal test done between the 10th and 13th weeks of pregnancy. It involves collecting a small sample of placental tissue (chorionic villi) either through the cervix or abdomen. CVS provides genetic information about the fetus and allows for earlier detection of chromosomal and genetic conditions.
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Comparison of Timing and Techniques
The main differences between amniocentesis and CVS lie in their timing and sample collection methods. CVS is performed earlier in pregnancy and samples placental tissue, while amniocentesis is done later and samples amniotic fluid. Both provide genetic information but differ in risk profiles and the stage of pregnancy at which results are available.
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