Humans are triploblastic; which means that in our early embryos, we are made of three separate germ layers. Which of the following structures is not derived from mesoderm?
Arteries and veins
The muscles
The brain
The bones
The correct answer and explanation is:
The correct answer is The brain.
Humans are triploblastic organisms, meaning they develop from three primary germ layers during embryogenesis: the ectoderm, mesoderm, and endoderm. Each of these layers gives rise to specific tissues and organs in the body. The mesoderm is the middle layer, and it is responsible for forming structures such as muscles, bones, and the cardiovascular system (including arteries and veins). However, the brain does not originate from the mesoderm; it is derived from the ectoderm.
The brain and spinal cord develop from a specialized region of the ectoderm known as the neural tube, a process called neurulation. This begins early in the embryonic stage when the ectoderm thickens to form the neural plate, which then folds to create the neural tube. The neural tube eventually differentiates into the central nervous system, which includes the brain and spinal cord.
In contrast, the mesoderm contributes to the formation of many vital systems and structures in the body. For instance, it forms the muscles, both smooth and skeletal, which are crucial for movement and function. The mesoderm also gives rise to bones, the cardiovascular system (including arteries, veins, and the heart), as well as the kidneys, reproductive organs, and connective tissues like tendons and ligaments.
The endoderm, the innermost germ layer, primarily forms the lining of the digestive and respiratory systems, such as the lungs, liver, and intestines.
In summary, while the mesoderm contributes to many of the body’s structures, the brain is specifically derived from the ectoderm, not the mesoderm.