Computer assisted semen analyzers in andrology research and veterinary practice

Capacitation as a regulatory event that primes spermatozoa for the acrosome reaction and fertilization : Regulators of sperm function

Capacitation is defined as the series of transformations that spermatozoa normally undergo during their migration through the female genital tract, in order to reach and bind to the zona pellucida, undergo the acrosome reaction, and fertilize the egg. During this process, extensive changes occur in all sperm compartments (head and flagellum; membrane, cytosol, cytoskeleton), factors originating from epididymal fluid and seminal plasma are lost or redistributed and membrane lipids and proteins are reorganized; ion fluxes induce biochemical modifications and controlled amounts of reactive oxygen species are generated; spermatozoa develop hyperactivated motility; and complex signal transduction mechanisms are initiated. The main purpose of capacitation is to ensure that spermatozoa reach the eggs at the appropriate time and in the appropriate state to fertilize these eggs, by finely-controlling the rate of the changes necessary to prime spermatozoa and by activating all the mechanisms needed for the subsequent acrosome reaction. The reversibility of some of the mechanisms leading to sperm capacitation may therefore be a very important aspect of the fine regulation and perfect timing of this process.

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Capacitation as a regulatory event that primes spermatozoa for the acrosome reaction and fertilization.

Prospective analysis of sperm-oocyte fusion and reactive oxygen species generation as criteria for the diagnosis of infertility.

The identification of human sperm hyperactivated motility has potential importance in sperm function tests, as well as in quality control assays and in reproductive toxicology investigations. However, relatively little is known about this phenomenon and the variety of definitions used for hyperactivation has led to a great deal of confusion as to its occurrence and physiological relevance. This presentation is a critical review of a number of aspects of hyperactivated motility, including its identification and potential role(s) in mammalian fertilization. The initial sections of the review consider the mechanisms involved in the development and maintenance of mammalian sperm motility, and the structural and functional changes in spermatozoa which occur during transport through the female reproductive tract. The methods available for the quantification of aspects of sperm movement are also discussed, with an historical overview of sperm movement analysis.

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A critical review of the physiological importance and analysis of sperm movement in mammals

The occurrence and time course of capacitation, acrosomal loss, and hyperactivated motility require quantitative definition in order to characterize fertile human sperm. In this study, video microscopy and digital image analysis were used to measure curvilinear (VCL) and straight line (VSL) velocity, average linearity of progression (UN [100 x VSL/VCUJ), maximum and mean amplitude of lateral head displacement (ALH), beat-cross-frequency (BCF), DANCE (VCL x meanALH) and DANCEMEAN (meanALH/(UIN/100)). These parameters were measured for sperm in semen and in the swim-up fraction of washed cells during incubation for up to 24 h under in vitro fertilization (IVF) conditions. Acrosomal loss was monitored in the same population of washed cells by an immunofluorescence end-point assay. The greatest increase in mean values of motility parameters was observed when seminal sperm were washed free of seminal plasma. Increases continued for up to 6 h of incubation. Two subpopulations of hyperactivated sperm were identified; one type, not found in semen, showed star-spin trajectories, and constituted 3.0, 3.8, 4.5, and 4.1% of the swim-up population after 0, 3, 6 and 24 h of incubation. The second type, termed transitional showed a more progressive trajectory and constituted less than 1% in semen. In total, hyperactivated cells constituted 0.8% of cells in semen, 14.5% of the swim-up population with no incubation, and 23.1, 22.7, and 19.4% after 3, 6, and 24 h of incubation, respectively. Acrosomal loss in the swim-up population was delayed during the first 3 h of incubation, then increased from near 5% at 3 h to 7 and 12% at 6 and 24 h, respectively. The kinetics of change in the extent of hyperactivation and in acrosomal loss, although measured in different cell populations, are consistent with an association between these two events.

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Joseph S. Tash

Papers

Temporal changes in motility parameters related to acrosomal status: identification and characterization of populations of hyperactivated human sperm.

Temporal Changes in Motility Parameters Related to Acrosomal Status: Identification and Characterization of Populations of Hyperactivated Human Sperm