What is the primary function of lymphatic capillaries?

The primary function of lymphatic capillaries is to absorb excess protein-containing interstitial fluid. These capillaries are specialized vessels that play a crucial role in maintaining fluid balance within the body. By collecting the excess fluid that leaks from blood capillaries into the surrounding tissues, they help prevent edema and ensure that fluids are returned to the circulatory system.

Lymphatic capillaries are also designed to be permeable, allowing for the uptake of larger molecules such as proteins and cellular debris, which cannot be easily reabsorbed by blood capillaries. This function is critical in preventing the accumulation of excess fluid and proteins in the interstitial space, which can lead to tissue swelling. Consequently, lymphatic capillaries facilitate the movement of lymph, a fluid that contains not only interstitial fluid but also immune cells that are vital for the body's defense mechanisms.

The focus on fluid absorption distinguishes this correct option from the others. For instance, the absorption of nutrients from the bloodstream primarily occurs through the digestive system and specifically within specialized structures like the villi in the intestines. Filtering bacteria from the lymph is a function of lymph nodes rather than lymphatic capillaries, while the production of antibodies is carried out by B cells in the immune