1. Lecture: The major events of thegerminal period.

Development begins at the point when sperm and ovum unite to form the zygote. The prenatal period is divided into three stages: germinal, embryonic, and fetal.

In the germinal period, the zygote develops into a ball of cells with a hollow core, or the blastocyst. A cluster of cells inside the blastocyst becomes the embryo.

Implantationoccurs when the zygote successfully adheres to the uterine wall. This is one of the most vulnerable processes in development, with only about 30 percent of zygotes successfully implanting.

Twins form during the germinal period. Monozygotic twins often result from the splitting of the blastocyst at the end of the first week. Dizygotic twins result from two ova that mature at the same time and are fertilized by two different sperm. Dizygotic twins are becoming more common as a result of fertility drugs and older mothers.

Question: Germinal Period

In one paragraph, discuss some of the potential complications that may occur in the germinal period. For instance, most mothers are unaware that they are pregnant during this stage. How might the mother's behaviors impact this stage of development?