The zona pellucida surrounds which of the following structures during early human development?

• A. Morula
• B. Blastocyst
• C. Gastrula
• D. Oocyte

Answer: (D)

Verified step by step guidance

1. Understand the role of the zona pellucida: The zona pellucida is a glycoprotein layer surrounding the plasma membrane of mammalian oocytes. It plays a crucial role in fertilization and early embryonic development.
2. Identify the stages of early human development: The stages include the oocyte, zygote, morula, blastocyst, and gastrula. Each stage has distinct characteristics and structures.
3. Recognize the structure associated with the zona pellucida: The zona pellucida is present around the oocyte before fertilization and remains until the blastocyst stage, where it facilitates implantation.
4. Differentiate between the stages: The morula is a solid ball of cells, the blastocyst is a hollow structure with an inner cell mass, and the gastrula is formed after implantation with distinct germ layers.
5. Conclude the association: The zona pellucida surrounds the oocyte initially and continues to play a role until the blastocyst stage, but it is not associated with the morula or gastrula stages.