Separation of first polar body occurs at the time of:: (A) Menstruation, (B) Ovulation, (C) Fertilization, (D) Implantation
Answer is B. 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.