What is a significant characteristic of the germinal period?

The germinal period is the earliest stage of human development, lasting from conception until about two weeks later, when the fertilized egg implants itself in the uterine wall. During this time, one of the most significant characteristics is rapid cell division, also known as cleavage. After the fertilized egg, or zygote, is formed, it begins to undergo successive mitotic divisions, leading to the formation of a multicellular structure known as the blastocyst. This rapid proliferation of cells is crucial as it lays the foundation for the subsequent stages of development, where differentiation begins to occur.

In contrast, while the establishment of the umbilical cord occurs later in the embryonic stage, the development of the nervous system and the formation of external features are aspects that take place after the germinal period. Therefore, the defining characteristic of this initial phase is indeed the swift cleavage and multiplication of cells, setting the stage for further development and organization of the embryo.