Which of the following cells is not normally seen in cerebrospinal fluid (CSF), serous fluids, and synovial fluids?

In normal circumstances, neutrophils are not typically present in cerebrospinal fluid (CSF), serous fluids, and synovial fluids. These fluids are generally clear and serve as a medium for nutrient transport and mechanical protection, and they should contain very few white blood cells under healthy conditions. The predominant cell types in these fluids when they are normal include lymphocytes and monocytes/histiocytes, which are part of the body's immune surveillance.

The presence of neutrophils, in contrast, usually indicates an inflammatory response or infection, such as bacterial meningitis in the case of CSF, or infections in the case of serous or synovial fluid. Therefore, neutrophils are seen in these fluids primarily when there is a pathological process occurring, making it correct to state that they are not expected to be found in normal, healthy samples.