Differing sperm ability to penetrate the oocyte in vivo and in vitro as revealed using colloidal preparations

Considerations of viscosity in the preliminaries to mammalian fertilisation

“…Gradations in viscosity could have a profound influence on the pattern and strength of flagellar activity and on the rate of forward movement of an individual sperm cell, as suggested by [58]. Evidence from in vitro observations indicates that prior interactions with viscous fluids may enhance the ability of boar spermatozoa to progress and to penetrate the zona pellucida of oocytes in vitro [59]. Suarez & Dai [60] noted that the mouse sperm flagellum may generate a stronger propulsive movement when confronted by increasing viscosity and viscoelasticity in the suspending medium.…”

Increasing Extender Viscosity Improves the Quality of Cooled Boar Semen

“…In addition, the difference between the extenders was greater at the end of the preservation period. Coy et al (2009) used a plant extract to increase the viscosity of a medium for swine spermatozoa and observed an increase in the STR index and the percentage of progressively motile spermatozoa, although they also reported lower VCL, VSL and VAP values in comparison to the control medium. Corcini et al (2011) found an increase in the percentage of motile spermatozoa after adding gelatin to the BTS extender for short term (three days) preserved swine semen.…”

“…In our study, this parameter was not different between the extenders. The literature suggests that changes to motility parameters are dependent on the agent used to increase the viscosity (because it determines whether liquefaction will occur at the temperature at which motility is measured), as well as the degree of viscosity (Corcini et al, 2011;Coy et al, 2009;Salvador et al, 2006;Yániz et al, 2005). Different viscous media, therefore, influence the motility characteristics of the spermatozoa.…”

“…In experimental in vitro conditions, however, the level of viscosity is very low, close to that of water, which is very much lower than that of the oviduct. According to Coy et al (2009), a certain degree of viscosity is desirable in order for the spermatozoon to interact with the oocyte in vitro (culture medium) or in vivo (oviduct) once it is no longer in contact with seminal plasma components. For this reason, they suggest that the viscosity of the medium is a parameter that must be taken into account when in vitro or in vivo experiments are being designed.…”

“…Corcini et al (2011) observed that adding gelatin to the short-term Beltsville Thawing Solution (BTS) extender for boar semen produced a less marked fall in the percentage of motile and morphologically normal spermatozoa during the preservation period compared to the samples to which no gelatin was added, although no significant differences between extenders were observed in either parameter (Corcini et al, 2011). Coy, Gadea, Rath and Hunter (2009) showed that the re-suspension of boar spermatozoa in a viscous medium increased the stability of the sperm membrane, decreased reactive oxygen species production and increased the capacity of spermatozoa to penetrate oocytes in vitro. The use of gelling extenders, mostly by the use of gelatin, has proven to be effective in prolonging the preservation of rabbit Nagy, Sinkovics, & Kovacs, 2002;Rosato & Iaffaldano, 2011), ovine and caprine (Salvador, Yániz, Viudes-de-Castro, Gómez, & Silvestre, 2006) sperm in a solid state.…”