1540s, belonging to an ecclesiastical metropolis, from Late Latin metropolitanus, from Greek metropolites resident of a city, from metropolis (see metropolitan (n.)). Meaning belonging to a chief or capital city is from 1550s. In reference to underground city railways, it is attested from 1867.
The solution that runs through these vessels, called lymph, begins in the circulatory system as blood plasma and then is converted to a fluid known as an interstitial or intercellular fluid. This fluid is responsible for delivering hormones, oxygen, and various nutrients to cells throughout the body.fferent vessels transport fluid into the lymph nodes, while efferent vessels carry filtered lymph away from the lymph nodes. White blood cells called lymphocytes are a major part of the lymphatic system. Lymph nodes may become swollen when a person gets sick.
Interstitial fluid drains into lymphatic capillaries, forming lymph. Lymph capillaries merge to form lymphatic vessels, which carry lymph into and out of structures called lymph nodes and finally back to the vascular system.Like blood capillaries, lymphatic capillaries are made of a single layer of squamous epithelial cells.nterstitial fluid drains into lymphatic capillaries, forming lymph. Lymph capillaries merge to form lymphatic vessels, which carry lymph into and out of structures called lymph nodes and finally back to the vascular system.