This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Anatomy
[{'content': 'Primordial germ cells originate in the \nSelect and explain. \nA. Gonads at the 4th week of embryonic develpment, B. Epiblast at 2nd week of embryonic development, C. Gonads at 2nd month of embryonic development, D. Yolk sac at 4th week of embryonic development', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Primordial germ cells originate in the epiblast Primordial germ cells (PGCs), also known as primitive sex cells originate in the epiblast at the caudal end of the primitive streak. PGCs are the precursors of gametes in both genders. PGCs arise in the epiblast during the 2nd week of development. They pass through the primitive streak during gastrulation and reach the wall of the yolk sac. They migrate from the yolk sac at the 4th week and reach the developing gonads by the end of the 5th week. Ref: Gray&;s Anatomy 41st edition Pgno: 184', 'role': 'assistant'}]