Join thousands of students who trust us to help them ace their exams!Watch the first video
Multiple Choice
At approximately which day does cellular differentiation begin in a human embryo?
A
Day 50
B
Day 25-26
C
Day 4-5
D
Day 10
Verified step by step guidance
1
Understand the concept of cellular differentiation: Cellular differentiation is the process by which unspecialized cells (stem cells) become specialized to perform specific functions. This is a critical step in embryonic development.
Review the timeline of human embryonic development: After fertilization, the zygote undergoes rapid cell division (cleavage) to form a blastocyst. Cellular differentiation begins shortly after the formation of the blastocyst.
Identify the stage of development where differentiation begins: Around Day 4-5, the blastocyst forms two distinct cell types: the inner cell mass (which will develop into the embryo) and the trophoblast (which will contribute to the placenta). This marks the beginning of cellular differentiation.
Compare the given options: Day 50 is far too late, as differentiation begins much earlier. Day 25-26 is also too late, as organogenesis is already underway by this time. Day 10 is closer but still after differentiation has started. Day 4-5 is the correct answer based on the timeline of embryonic development.
Conclude that cellular differentiation begins at Day 4-5 in a human embryo, as this is when the blastocyst forms distinct cell types, initiating specialization.