Copyright q American Society of Andrology Capillary-Loaded Particle Fluid Dynamics: Effect on Estimation of Sperm Concentration

ABSTRACT: Capillary loaded chambers are frequently used for se-men analysis. Poiseuille flow of specimen into these chambers caus-es migration of suspended particles or cells in a direction transverse to the flow, which results in their preferential accumulation in the Segre-Silberberg (SS) planes. This SS effect depends on the trans-verse velocity gradient in the laminar flow. For semen analysis in thin capillary-loaded slides, the SS effect can lead to erroneous es-timation of sample sperm-cell concentration. To better understand chamber flow dynamics and SS effect significance, we assessed flow uniformity, inflow cell velocity, and results of concentration mea-surements under different flow conditions for latex bead and porcine and human sperm suspensions. Overall, a concentration peak was present at the meniscus, which continued through chamber loading. High-velocity SS preferred planes, which channeled particles toward the meniscus, were located at the fractional positions of b 5.27 an