The lymphatic circulation carries lymph, which is a fluid that has other names prior to flowing into a lymphatic vessel. What is the name of this fluid when it is still part of the blood?

While the fluid is still circulating in the blood, it is called plasma. Some plasma filters out through capillary walls and becomes interstitial fluid; once it enters lymphatic vessels, it is called lymph. Arteries and capillaries are blood vessels, not names for the fluid.

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