Primary oocyte in division
Secondary oocyte and polar body 1
Figure 1.20 Maturation of the oocyte. A. Primary oocyte showing the spindle of the first meiotic division. B. Secondary oocyte and first polar body. The nuclear membrane is absent. C. Secondary oocyte showing the spindle of the second meiotic division. The first polar body is also dividing.
membrane of the secondary oocyte in the perivitelline space (Fig. 1.20B). The cell then enters meiosis II but arrests in metaphase approximately 3 hours before ovulation. Meiosis II is completed only if the oocyte is fertilized; otherwise, the cell degenerates approximately 24 hours after ovulation. The first polar body also undergoes a second division (Fig. 1.20C).
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Once your pregnancy is over and done with, your baby is happily in your arms, and youre headed back home from the hospital, youll begin to realize that things have only just begun. Over the next few days, weeks, and months, youre going to increasingly notice that your entire life has changed in more ways than you could ever imagine.