This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cytogenetic Disorders, Subject name: Pathology
Kary otyping is done in which phase of cell cycle- 
Select and explain. 
A. Anaphase, B. Metaphase, C. Telophase, D. S phase
B: Metaphase
Answer: B: Metaphase 
Explanation: Ans. is 'b' i.e., Metaphase o To produce a karyotype, one must obtain cells capable of growth and division as karyotyping is done by arresting mitosis in dividing cells in metaphase.o Karyotyping is the study of chromosomes and is used in cytogenetics to study the chromosomal abnormalities,o After arresting the cells in metaphase the chromosomes are examined to see for:i) Numbers - to detect abnormalities in chromosome numbers such as aneuploidy (trisomy, tetrasomy), polyploidy,ii) Structure - to detect structural chromosomal anomalies such as translocations, deletions, inversions.Karyotypingo It is the study of chromosomes,o It is used in cytogenetics to study the chromosomal abnormalities.o A karyotype is a standard arrangement of a photographed or imaged stained metaphase spread in which chromosome pairs are arranged in order of decreasing length.o To produce a karyotype, one must obtain cells capable of growth and division as karyotyping is done by arresting mitosis in dividing cells in metaphase,o Samples used are : -Amniotic fluids (cells from amnion, skin, urogenital system, respiratory system and GI system).# Chorionic vill.# Bone marrow# Skin fibroblasts# Peripheral blood lymphocytes# Fetal umblical blood.# Lymph node tissue# Solid tumor sample