Sperm kinematics and morphometric subpopulations analysis with CASA systems: a review

Abstract

Sperm kinematics and morphometric subpopulations analysis with CASA systems: a review. The subjective evaluation of seminal quality has given way to the use of objective assessment techniques by CASA technology (computer-assisted semen analysis). The application of principal components (PC) and clustering methods to reveal subpopulations of spermatozoa is a powerful tool to evaluate raw semen and processed cell suspensions, but not many researchers are aware of the technique. PC analysis is a multivariate statistical method that reduces the number of variables used in subsequent calculations used to describe the data. By integrating the original variables according to their coherence in a database into a new complex mathematical variable, clearly defined homogenous subpopulations of spermatozoa can be defined. Kinematic, morphometric, morphological or DNA integrity tests may apply to characterize it and understand the reproductive biology of the spermatozoon. In recent years there has been a substantive change in the conceptual paradigm regarding what an ejaculate is. It should be said that until recently it was considered that the representative population (billions) of sperm was made up of "equivalent" cells with a common goal: to be the one that could finally fertilize the oocyte. The verification that the set of spermatozoa is grouped in distinct subpopulations, according to their kinematic and morphometric characteristics, opens the way towards a more cooperative vision. Besides, we have seen that the subpopulation distribution is different among males, which seems to indicate different strategies that can be understood within another paradigm, that of sperm competition between different ejaculates. The existence of heterogeneous subpopulations of spermatozoa in the ejaculate that show kinematics and morphometric patterns is widely known but the biological meaning of these different sperm subpopulations is still not clear. Although the role of the different subpopulations remains unknown, the work should continue in that direction.

A New Approach of Sperm Motility Subpopulation Structure in Donkey and Horse

“…The sperm analysis is a prerequisite for breeding soundness examination, and the use of semen in artificial insemination in horses is like in all farm animals. The introduction of computer-assisted semen analysis (CASA) technology allowed for an unprecedented degree of sophistication in the study of sperm characteristics and particularly in reference to kinematics patterns (5,6). Computer-aided sperm motility analysis (CASA-Mot) systems capture sequences from microscopic fields and automatically analyze all sperm trajectories (7,8), offering a battery of quantitative kinematic parameters (9).…”

Predictive Capacity of Boar Sperm Morphometry and Morphometric Sub-Populations on Reproductive Success after Artificial Insemination

“…The differences in the cluster populations were analyzed across all boar semen morphometric variables for size, head shape, and semen doses used in AI. Several studies have described the presence of different sub-populations within an ejaculate [11,19,[61][62][63][64][65][66][67]. These sub-populations may be affected by external factors associated with semen, such as extender type or species [68,69].…”

Morfometría y subpoblaciones de espermatozoides de llama (Lama glama) usando el sistema ISAS® CASA-Morph

“…Este es el primer estudio que ofrece información de la estructura de subpoblaciones espermáticas de llamas y de camélidos en función de la morfometría de dicha célula, en la cual se identificaron cuatro subpoblaciones espermáticas, como las halladas por Gutiérrez-Reinoso y García-Herreros (2016) en gatos, mientras que se han reportado tres SP en pumas (Cucho et al, 2016) y cinco SP en gallinas de guinea (García-Herreros, 2016). La evidencia que los espermatozoides se agrupan en subpoblaciones bien definidas de acuerdo con sus características cinéticas y/o morfométricas, permite dar una visión más amplia del comportamiento espermático; además, se ha visto que la distribución subpoblacional varía entre individuos, lo cual indicaría diferentes estrategias de competencia entre eyaculados (Valverde et al, 2019). La información hallada en este estudio proporciona nuevos conocimientos que podrían usarse en futuros estudios que emplean la morfometría del espermatozoide de llama como un indicador del estado reproductivo de esta especie.…”