Optometry Admission Test (OAT) Practice

What significant development process follows the implantation stage?

1. Fertilization

2. Blastulation

3. Gastrulation

4. Neurulation

The correct answer is: Gastrulation

The significant development process that follows the implantation stage is gastrulation. During implantation, the embryo attaches to the uterine wall, and once this process is successful, it sets the stage for further development. Gastrulation is critical because it involves the formation of the three primary germ layers: ectoderm, mesoderm, and endoderm. These layers ultimately give rise to all the tissues and organs in the developing organism. During gastrulation, the cells migrate and differentiate, establishing the foundation for the body plan of the embryo. Fertilization occurs before implantation and involves the union of sperm and egg. Blastulation refers to the formation of the blastocyst, which occurs shortly after fertilization but before implantation. Neurulation follows gastrulation and involves the formation of the neural tube, important for the development of the central nervous system. Thus, gastrulation is the direct process that occurs after implantation, making it the correct answer.