Which of the following best describes lymph fluid?

Lymph fluid is best described as a protein-rich fluid absorbed into lymph capillaries. Lymph originates from interstitial fluid, which permeates tissues and contains nutrients, hormones, and waste products. As this fluid enters the lymphatic system through lymph capillaries, it often contains a higher concentration of proteins compared to blood plasma due to the leakage of proteins from capillaries and the addition of other substances from extracellular fluids.

This characteristic is significant because the protein content in lymph is critical for various physiological processes, including maintaining fluid balance and immune responses. The lymphatic system plays a key role in transporting lymph back to the circulatory system, where it can help regulate protein concentrations and prevent edema in tissues.

In contrast, lymph does not consist primarily of red blood cells, nor is it filtered directly from the gastrointestinal tract. While some fats from digested food are absorbed into lymph (forming chyle), lymph fluid is not formed directly from blood plasma without modification; rather, it typically undergoes transformation from interstitial fluid as it moves through the lymphatic vessels.