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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Implantation occurs at what stage of zygote?
assistant
The correct answer is  Ans. is 'b' i.e., Blastocyst * The morula after spending about 3 days in the tube enters the uterine cavity via the narrow ostium (1 mm) on the fourth day in the 16-64 cell stage. Blastocyst formation is on the 5th day.* Implantation occurs in the endometrium on the anterior or posterior wall of the body near the fundus on the sixth day following fertilization (corresponding to the 20th day of the menstrual cycle).* The deeper penetration of the human blastocyst is called interstitial implantation, which happens by approximately the 13th day after fertilization.