What fluid does gravitational sedimentation primarily target for concentration?

Gravitational sedimentation is a technique primarily used to concentrate cells or particles from a fluid by allowing them to settle under the influence of gravity. In the context of cytology, cerebrospinal fluid (CSF) is a particularly appropriate choice for gravitational sedimentation. This is because CSF is typically clear and contains relatively low concentrations of cells, making it necessary to concentrate any cells present to assess pathological conditions effectively.

When conducting a cytological examination, concentrating the CSF through sedimentation allows for improved visibility of cells, enhancing the diagnostic yield. This method effectively isolates cells for identification of infections, malignancies, and other conditions that may influence CSF composition.

Other fluids like whole blood, synovial fluid, or serum might not be as well suited for this technique in the context of cytological evaluation. Whole blood contains high cellularity, making other methods (like differential centrifugation) more suitable for isolation. Synovial fluid may also require more specific handling given its thicker viscosity and potential for inflammatory cells. Serum, which is the liquid component of blood after coagulation, does not contain intact cells as it separates from the cellular components of blood, making it less relevant for cytology that requires the study of cellular structures.