28. Which term is used for the outer cells of the human blastocyst
Answer: C
The term used for the outer cells of the human blastocyst is Trophoblast.
The outer cells of the human blastocyst are referred to as the trophoblast, which plays a crucial role in implantation and the formation of the placenta.
A) Embryonic disk
The embryonic disk refers to a flattened structure that forms from the inner cell mass of the blastocyst and eventually develops into the embryo. It is not associated with the outer layer of cells, making this option incorrect.
B) Neural plate
The neural plate is a structure that forms later in embryonic development from the ectoderm, which ultimately gives rise to the nervous system. Since it does not describe the outer cells of the blastocyst, this option is also incorrect.
C) Trophoblast
The trophoblast is the correct term for the outer layer of cells in the blastocyst. This layer is essential for the implantation of the embryo into the uterine wall and contributes to the formation of the placenta, making this option accurate.
D) Mesenchyme
Mesenchyme refers to a type of tissue that is involved in the development of connective tissues, bones, and other structures. It does not pertain to the outer cells of the blastocyst, thereby rendering this option incorrect.
Conclusion
The trophoblast is definitively the correct answer as it specifically identifies the outer layer of the blastocyst, crucial for implantation and placental development. In contrast, other options describe different structures or stages in embryonic development, which do not accurately represent the outer cells of the blastocyst.