Effect of counting chamber depth on the accuracy of lensless microscopy for the assessment of boar sperm motility

Abstract

Sperm motility is one of the most significant parameters in the prediction of male fertility. Until now, both motility analysis using an optical microscope and computer-aided sperm analysis (CASA-Mot) entailed the use of counting chambers with a depth to 20µm. Chamber depth significantly affects the intrinsic sperm movement, leading to an artificial motility pattern. For the first time, laser microscopy offers the possibility of avoiding this interference with sperm movement. The aims of the present study were to determine the different motility patterns observed in chambers with depths of 10, 20 and 100µm using a new holographic approach and to compare the results obtained in the 20-µm chamber with those of the laser and optical CASA-Mot systems. The ISAS®3D-Track results showed that values for curvilinear velocity (VCL), straight line velocity, wobble and beat cross frequency were higher for the 100-µm chambers than for the 10- and 20-µm chambers. Only VCL showed a positive correlation between chambers. In addition, Bayesian analysis confirmed that the kinematic parameters observed with the 100-µm chamber were significantly different to those obtained using chambers with depths of 10 and 20µm. When an optical analyser CASA-Mot system was used, all kinematic parameters, except VCL, were higher with ISAS®3D-Track, but were not relevant after Bayesian analysis. Finally, almost three different three-dimensional motility patterns were recognised. In conclusion, the use of the ISAS®3D-Track allows for the analysis of the natural three-dimensional pattern of sperm movement.

Current perspectives of CASA applications in diverse mammalian spermatozoa

“…Initially, tracking of spermatozoa in three dimensions was performed by high-speed image stack acquisitions in sea urchin spermatozoa (Corkidi et al 2008) and a lens-free on-chip imaging technique in human spermatozoa (Su et al 2012) and boar (Soler et al 2018) spermatozoa. Newly developed CASA software enables the modelling and simulation of fourdimensional sperm motility tracks from the x and y coordinates obtained from normal two-dimensional tracks ( Fig.…”

Evaluación de cámaras de recuento sobre parámetros espermáticos de verracos analizados con un sistema CASA-Mot

“…En función de la especie y el estado fisiológico, se necesita un espacio considerable para desarrollar correctamente la movilidad espermática, debido a que el movimiento natural de los espermatozoides es helicoidal (Kraemer et al, 1998;Soler et al, 2018). En la literatura veterinaria, la altura de la cámara de recuento para el análisis de la cinética y movilidad del semen es variable y por lo general, no se suele mencionar (Hoogewijs et al, 2012).…”

Effect of frame rate capture frequency on sperm kinematic parameters and subpopulation structure definition in boars, analysed with aCASA‐Mot system

“…Several authors have indicated that the results are dependent on the set‐up of the system used, such as the field of observation location (Nöthling & dos Santos, ), frame rate of recordings (Wilson‐Leedy & Ingermann, ), the kind and depth of the counting chamber used, the volume of the drop and other factors (Bompart et al., ; Soler et al., ).…”

“…Another aspect is that the correct determination of sperm tracks results in a fundamental shift in the determination of motility and morphology subpopulation structure. The fact that an ejaculate is constituted of different subpopulations of spermatozoa has been well established in a great variety of species (boar (Abaigar, Holt, Harrison, & del Barrio, ; Flores et al., ; Holt, Holt, & Moore, ; Soler et al., ), bull (Valverde et al., ; Yániz et al., ), donkey (Flores et al., ), eel (Gallego et al., ), fox (Soler et al., , ), gazelle (Abaigar et al., ), goat (Vázquez et al., ), ram (Luna et al., ), stallion (Ortega‐Ferrusola et al., ), human (Vásquez, Soler, Camps, Valverde, & García‐Molina, ; Yániz et al., ), salmon (Caldeira et al., )), but most of these studies were not designed for considering the effect of the FR.…”