AAMC FL Practice Exam

Which of the following organs is developed from the endoderm layer?

1. Heart

2. Liver

3. Kidney

4. Skeletal muscles

The correct answer is: Liver

The liver is an organ that develops from the endoderm layer during embryonic development. The endoderm is one of the three primary germ layers, the others being ectoderm and mesoderm. This germ layer gives rise to the lining of the digestive tract, respiratory system, and several associated organs. The liver originates from the hepatic diverticulum, which is an outgrowth of the endoderm. As development progresses, this diverticulum will differentiate into the liver, gallbladder, and bile ducts, all of which are critically involved in functions such as metabolism, detoxification, and secretion of bile. In contrast, the heart is primarily derived from mesoderm, which is responsible for developing the cardiovascular system. The kidneys also originate from mesoderm, specifically from the intermediate mesoderm, which gives rise to the urogenital system. Skeletal muscles are developed from the mesoderm as well, arising from somites, which are segmented blocks of mesoderm that develop into the skeletal elements, dermis, and muscles. Understanding these developmental pathways is crucial in embryology and can help clarify how different organ systems and structures arise from specific germ layers in a developing embryo.