Sperm surface changes and physiological consequences induced by sperm handling and storage

Abstract

Spermatozoa interact with their immediate environment and this contact remodels the sperm surface in preparation for fertilisation. These fundamental membrane changes will be critically covered in this review with special emphasis on the very specific surface destabilisation event, capacitation. This process involves very subtle and intricate modifications of the sperm membrane including removal of suppression (decapacitation) factors and changes in the lateral organisation of the proteins and lipids of the sperm surface. Processing of sperm for assisted reproduction (storage, sex-sorting, etc.) subjects spermatozoa to numerous stressors, and it is possible that this processing overrides such delicate processes resulting in sperm instability and cell damage. To improve sperm quality, novel mechanisms must be used to stabilise the sperm surface during handling. In this review, different types of membrane stress are considered, as well as novel surface manipulation methods to improve sperm stability.

Optimization of microelectrophoresis to select highly negatively charged sperm

“…2a, b). Our observations here are in accordance with the published literature [12,[46][47][48] suggesting that the epididymal proteins adhered to the sperm surface are removable.…”

“…It is well documented that some epididymal proteins are weakly associated with the sperm membrane [46,47], whereas others are anchored to the membrane by glycosylphosphatidylinositol sub-units [12,48]. Modifications in membrane configuration could disrupt the association between epididymal proteins and the sperm membrane.…”

“…Modifications in membrane configuration could disrupt the association between epididymal proteins and the sperm membrane. During cryopreservation (reviewed by Leahy and Gadella [48],) and early capacitation [49], modification and redistribution of molecules to the sperm membrane could also cause the loss of the epididymal proteins from the sperm surface [50,51], resulting in the loss of electro negativity. For the first time, we showed that the process of DGC appears to physically wash off the negative charge from the sperm, a beneficial effect for chargebased sperm selection.…”

Sedimentation properties in density gradients correspond with levels of sperm DNA fragmentation, chromatin compaction and binding affinity to hyaluronic acid

“…In this regard, striking changes in the labelling of hyaladherin were observed after incubation under conditions favouring capacitation and after the acrosome reaction. General fluorescence, particularly with hyaluronic acid-TRITC increased after capacitation and the acrosome reaction, suggesting greater accessibility of this detection reagent to its ligands in keeping with the likely redistribution of membrane components (Leahy and Gadella, 2011). Capacitation, as reported originally by Yanagimachi (1969) using hamster spermatozoa is now a widely recognised phenomenon that is linked with the acquisition of hyperactive motility (Fraser, 1998;Suarez, 2008;Bailey, 2010), the observed redistribution of hyaladherins accords with reports showing that cytoplasmically mature and actively motile spermatozoa have completed their plasma membrane remodelling, which probably includes the redistribution of hyaladherins (Cayli et al 2003;Huszar et al 2003;Prinosilova et al 2009;Parmegiani et al 2010a;Yagci et al 2010).…”

“…During transit through the female genital tract, sperm undergo capacitation, which involves protein tyrosine phosphorylation, hyperactive motility and the dramatic re-distribution of membrane proteins and lipids including the efflux of membrane cholesterol (Zaneveld et al 1991;Liu et al, 2007;Gadella et al, 2008;Leahy and Gadella, 2011). Other changes may also affect the distribution of hyaladherins in preparation for encountering the descending egg mass (Baldi et al, 2000).…”