All of the following have no lymphatics, except
**Core Concept**
The question is testing the student's knowledge of lymphatic anatomy. The lymphatic system plays a crucial role in the immune response, fluid balance, and lipid absorption. Certain organs and tissues in the human body lack lymphatic vessels, which can lead to specific clinical implications.
**Why the Correct Answer is Right**
The correct option is the central nervous system (CNS), including the brain and spinal cord. The CNS lacks lymphatic vessels, and as a result, the removal of waste products, such as amyloid beta, is impaired, contributing to neurodegenerative diseases like Alzheimer's. The absence of lymphatic vessels in the CNS is due to the presence of the blood-brain barrier, which restricts the passage of immune cells and other substances.
**Why Each Wrong Option is Incorrect**
**Option A:** The correct answer is not the eye, as the uvea, a part of the eye, does have lymphatic vessels. The uvea is responsible for supplying the eye with blood and lymphatic vessels, which play a crucial role in the immune response to infections.
**Option B:** The correct answer is not the lung, as the lung has a well-developed lymphatic system that plays a crucial role in the removal of fluid and proteins from the interstitial space. The lymphatic system in the lung is essential for maintaining lung function and preventing pulmonary edema.
**Option C:** The correct answer is not the liver, as the liver has a dual blood supply from the hepatic artery and the hepatic portal vein, and it also has a well-developed lymphatic system. The lymphatic system in the liver plays a crucial role in the removal of bile and other substances.
**Clinical Pearl / High-Yield Fact**
The absence of lymphatic vessels in the CNS has significant implications for the removal of waste products, including amyloid beta, which contributes to neurodegenerative diseases like Alzheimer's. This knowledge highlights the importance of understanding the complex anatomy of the lymphatic system and its role in maintaining immune homeostasis.
**Correct Answer: C. Liver**