AAMC FL Practice Exam 2025 – The Comprehensive All-in-One Guide to Exam Success!

During embryonic development, the mesoderm is the middle germ layer that plays a crucial role in forming various structures in the body. It develops into several important components, primarily including muscles, the cardiovascular system, skeletal structures, and the kidneys. Specifically, the mesoderm gives rise to skeletal muscle, smooth muscle, cardiac muscle, and components of the circulatory system, such as blood vessels and the heart.

This differentiative capability explains why the option highlighting muscles and parts of the circulatory system aligns with the functions and structures that originate from the mesoderm. As for the other options, the endoderm is responsible for developing into the lining of the digestive system, the ectoderm forms the nervous system and the skin, while skin and hair follicles are derived from the ectoderm as well. Thus, the correct answer accurately reflects the entities that arise specifically from mesodermal tissues during fetal development.