1.   Once development begins, the embryo divides rapidly and each mitosis seems to be associated with an increase in calcium.

2.   At that juncture, the human embryo has divided enough times to form a microscopic basketball.

3.   After the embryo had divided a number of times, the embryo was implanted into the uterus of a surrogate mother mouse to continue development.

4.   He theorized that identical twinning was more like a birth defect, the result of a noxious influence that causes the embryo to divide.

5.   The splitting of embryos can occur naturally when an early embryo spontaneously divides in half, producing identical twins, or thirds or quarters early in development.

6.   Their experiment was terminated after the embryo had divided into four cells.