Optometry Admission Test (OAT) 2025 – 400 Free Practice Questions to Pass the Exam

The endoderm is one of the three primary germ layers formed during embryonic development, alongside the ectoderm and mesoderm. Its main function is to give rise to the lining of the gastrointestinal tract and other internal organs, such as the respiratory system and parts of the urinary system.

Therefore, the option that states it generates the lining tissues is correct. The endoderm will differentiate into tissues that will line organs such as the stomach, intestines, and lungs, thereby playing a crucial role in forming the internal structures that are vital for bodily functions.

In contrast, the muscular system is primarily derived from the mesoderm, which is responsible for developing muscles and connective tissues. The nervous system originates from the ectoderm, which forms structures such as the brain and spinal cord. Lastly, the skeletal framework also arises from mesodermal tissues, specifically those that give rise to bones and cartilage. Each of these systems is governed by the specific germ layer responsible for its development, highlighting the unique roles that each germ layer plays during embryogenesis.