A) chiasmata
B) Ban-bodies
C) sex-chromosomes
D) drumsticks
Correct Answer: B
Solution :
Foetal sex can be determined by examining cells from the amniotic fluid by looking for Barr bodies and female sex chromosomes. The sex of the child and chromosomal abnormalities, if any, can be detected by studying foetal cells. According to British geneticist Mary Lyon (1961) one of the two X chromosomes of a normal female becomes heterochromatic and appears as Barr body. Drumsticks are the sex chromatin (named Barr bod/after M.L Barr) present in the neutrophil of 3-5% cells in females (absent in males). So, have no link with amniotic fluid. Chiasmata is the point where two of the four chromatids of a bivalent cross each other. It is the result of a crossing over, seen at diplotene stage of meiosis. PMC (Pollen Mother Cell) is the best structure to demonstrate chiasmata.
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