User:Freeski14/Labile cell

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In cellular biology, labile cells are cells that continuously multiply and divide throughout life. This continual division of labile cells allows them to reproduce new stem cells and replace functional cells that are lost in the body. Functional cells may be lost through necrosis, which is the premature death of cells caused by environmental disturbances, such as diseases or injuries. Functional cells may also need to be replaced after undergoing apoptosis. Apoptosis is the programmed death of cells that is controlled and occurs normally in an organism's development (3). Labile cells regenerate themselves through the process of mitosis (5). In addition to labile cells, there are two other types of cells that are involved in cell division, classified by their regenerative capacity. The other two cell types that are involved include stable cells and permanent cells. Stable cells, unlike labile cells, are typically not dividing and only do so when an injury occurs. In the event of an injury, stable cells are capable of dividing rapidly and replacing the damaged cells to prevent loss of function in the tissue or organ. Permanent cells completely lose the ability to divide after maturing; therefore, damage to tissue made up of permanent cells may result in the loss of function (1). Each of these three cell types respond to injuries to their corresponding tissues differently.

Some examples of labile cells, which are thought to be constantly dividing, include cells within the skin, intestine, liver, and bone marrow (6).

Labile cells exhibit a very short G1 phase and never enter G0 phase (the resting phase), as they are constantly dividing throughout their life (4).

Hazards
Cells that are constantly dividing have a higher risk of dividing uncontrollably and becoming malignant. Muscle tissue does not consist of constantly dividing cells, which is likely why cancer of the muscle is not nearly as common as, for example, cancer of the skin.

In addition, cytotoxic drugs used in chemotherapy target dividing cells and inhibit their proliferation. The cytotoxic drugs aim to target the dividing cells which are malignant in the body; however, these drugs target all dividing cells and are not capable of only selecting cancerous ones. Healthy cells, that are normally dividing in the body, are targeted and effected as well. For this reason, adverse effects are often produced from chemotherapy. The labile cells within epithelial tissue and bone marrow, for example, may be targeted, resulting in possible hair loss or bone marrow suppression (4).