National Dental Assisting Examining Board (NDAEB) Practice Exam

What does ectoderm differentiate into during development?

1. Heart and lungs

2. Muscle and bone

3. Skin and oral cavity lining

4. Nervous system and connective tissue

The correct answer is: Skin and oral cavity lining

During development, ectoderm primarily differentiates into structures associated with the outermost layer of the developing embryo. This includes the formation of the skin, which serves as a protective barrier, and the lining of the oral cavity, which plays a crucial role in digestion and communication. The ectodermal layer is also responsible for developing the nervous system, including the brain and spinal cord, but this aligns more traditionally with components like the neural ectoderm rather than the broader definition of ectodermal derivatives in a general context. While the heart and lungs are derivatives of the mesoderm, and muscles and bones also arise from mesodermal origins, connective tissue is similarly derived from mesodermal lineage. Thus, the correct answer highlights the ectoderm's role in forming skin and the oral cavity lining, making it a key player in the development of structures that interact with the external environment and are vital for various bodily functions.