Final answer:
Less than half of all zygotes survive beyond the first two weeks of the germinal period, as they must navigate the processes of cell division and successful implantation in the uterine lining.
Step-by-step explanation:
The question of how many conceptions terminate in the germinal period concerns early human development and the stages that follow fertilization. Mitosis is a critical process during the germinal stage; however, it is also a period with a significant rate of natural attrition for the developing zygote. As noted by Hall (2004), fewer than one-half of all zygotes survive beyond the first two weeks, as they must successfully undergo cell divisions and implant in the uterus to continue development. The germinal period lasts approximately eight to nine days from fertilization, entails the transformation of a fertilized egg into a zygote, and concludes with the blastocyst implanting in the uterine lining. If implantation is unsuccessful, the conceptus will deteriorate and die. This early developmental stage is marked by rapid cell division and the formative establishment of what will eventually become an embryo post-implantation.