system
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
Separation of first polar body occurs at the time of:
assistant
The correct answer is  Ans. B OvulationRef: Guyton Physiology, 11th ed. pg. 1027* While still in the ovary, the ovum is in the primary oocyte stage.* Right before it is released from the ovarian follicle, its nucleus divides by meiosis and a first polar body is expelled from the nucleus of the oocyte.* The primary oocyte then becomes the secondary oocyte.* In this process, each of the 23 pairs of chromosomes loses one of its partners, which becomes incorporated in a polar body that is expelled.* This leaves 23 unpaired chromosomes in the secondary oocyte. It is at this time that the ovum, still in the secondary oocyte stage, is ovulated into the abdominal cavity.