What is the fluid found in the spaces between tissue cells called?

The fluid found in the spaces between tissue cells is termed interstitial fluid. This is the specific fluid that occupies the interstitial spaces, which are the areas between cells in a tissue. Interstitial fluid plays a critical role in the movement of nutrients and waste products between blood and cells, facilitating communication and nutrient exchange at the cellular level. This fluid is a component of extracellular fluid, which encompasses all fluids outside of cells, including lymph and blood plasma; however, interstitial fluid specifically refers to the fluid that fills the space between adjacent cells in tissues.

While intracellular fluid refers to the fluid within the cells, cytoplasm describes the gel-like substance inside cells that includes organelles and the cytosol (the liquid part of the cytoplasm), neither of these terms applies to the fluid between tissue cells. Thus, the focus on interstitial fluid demonstrates its vital role in tissue health and homeostasis.