Optometry Admission Test (OAT) Practice

What are the four stages of early development for reproduction?

1. Gastrulation, Fertilization, Cleavage, Neurulation

2. Cleavage, Implantation, Gastrulation, Neurulation

3. Fertilization, Gastrulation, Neurulation, Mitosis

4. Embryogenesis, Implantation, Cleavage, Neurulation

The correct answer is: Cleavage, Implantation, Gastrulation, Neurulation

The four stages of early development for reproduction, particularly in the context of embryology, are crucial for understanding the development of an organism from a single fertilized egg into a complex structure. The correct sequence includes cleavage, implantation, gastrulation, and neurulation. Cleavage refers to the series of rapid mitotic divisions that a fertilized egg undergoes, resulting in a multicellular structure known as a blastula. This stage sets the foundation for further development by increasing cell numbers while maintaining the overall size of the developing embryo. Implantation is the process by which the developing embryo attaches to the uterine wall, allowing for further growth and the establishment of a connection to the mother's blood supply. This stage is critical for providing nutrients and oxygen to the growing embryo and is essential for successful pregnancy. Gastrulation is the transformative stage where the single-layer blastula reorganizes into a multi-layered structure known as the gastrula. This stage establishes the three primary germ layers: ectoderm, mesoderm, and endoderm, which later differentiate into various tissues and organs. Neurulation follows gastrulation and is characterized by the formation of the neural tube, which eventually develops into the central nervous system. This stage is vital for establishing the