Enhanced Binding of Sperm With Superior Volume Regulation to Oviductal Epithelium

Abstract

ABSTRACT:The plasma membrane is a key organelle with respect to sperm fertilizing ability. A sensitive way of testing plasma membrane functionality is to examine the sperm ability to moderate its swelling in response to hypo-osmotic stress (volume regulatory ability) using an electronic cell counter to assess cell volume changes. In this study of frozen-thawed bull sperm, we examined the relationship among sperm-oviductal epithelium binding capacity, osmotically induced swelling response, volume regulatory ability, and standard spermatologic parameters. Sperm cell volume distributions were measured under iso-osmotic conditions and after hypo-osmotic stress. The relative volume shift was calculated by comparing modal values of the cell volume distributions during transition from isoosmotic to hypo-osmotic conditions. Significant correlations were found between volumetric parameters and sperm-oviduct binding capacity. Both the relative volume shift and regulative volume decrease correlated positively and significantly with the spermoviduct binding capacity. No significant correlations were found between sperm volumetric parameters and any of the standard sperm parameters with the exception of forward motility of Percollwashed sperm. However, the use of multiple regression models improved the prediction level for binding capacity when motility parameters were combined with membrane integrity and volumetric parameters (R 2 5 .84). Spermatozoa of bulls with high nonreturn rates responded to hypotonicity as ''perfect osmometers.'' Subfertile bulls had lower binding indices and deficiencies in volume recovery after hypotonic challenge, indicating that intact volume regulatory ability is a necessary prerequisite for binding to oviductal epithelium and is related to fertility. Volumetric parameters therefore could be used as tools in semen evaluation programs.

Fertilization capacity with rainbow trout DNA-damaged sperm and embryo developmental success

“…It is suspected that, in mammals, DNA-damaged spermatozoa are impaired to fertilize under natural conditions by the high selective pressure occurring in the female tract and during sperm-egg recognition (Holt & Van Look 2004, Khalil et al 2006, Satake et al 2006, Suarez & Pacey 2006, Rodriguez-Martinez 2007, Yeates et al 2009). These selection mechanisms are related to sperm structures that could also be modified in spermatozoa carrying damaged DNA Fertilization with DNA-damaged spermatozoa (Tarin et al 2000, Andrabi 2007, Thomson et al 2009).…”

“…In mammals, it has been suggested that the strong selective process undergone by sperm in the female tract (by elimination of defective spermatozoa, sperm competition, cryptic female choice, etc.) is probably unrelated to a DNA-scanning mechanism, and that some kind of link between sperm phenotype and genotype could be involved in this process (Holt & Van Look 2004, Khalil et al 2006, Satake et al 2006, Suarez & Pacey 2006, Rodriguez-Martinez 2007. Hourcade et al (2010) showed that selection of DNA-undamaged spermatozoa occurs in mice during the transit through the oviduct as well as during the contact with the vitelline membrane, but this selective process is dependent on the source of sperm damage and probably related to the presence of damage in other cell structures.…”

Chromatin-unstable boar spermatozoa have little chance of reaching oocytes in vivo

“…Immaturity of sperm, therefore, may be associated with incomplete function of the sperm plasma membrane, which impairs binding to the oviductal epithelium, e.g., by a failure of interaction between protein/carbohydrate-binding sites on the sperm surface and glycosylated ligands on the oviductal epithelium. (Khalil et al 2006). Whereas cytoplasmic droplets present a quite common sperm abnormality in boar ejaculates, the incidence of chromatin instability seems to be relatively low in commercial boar semen (López-Fernández et al 2008).…”

The epididymis, cytoplasmic droplets and male fertility

“…12,75 Flagellar angulation occurs at the site of the cytoplasmic droplet, as it does in the infertile mice, proving that the ejaculated spermatozoa had retained their droplets. The infertility of spermatozoa with droplets has been suggested to reflect poor adherence to the zona pellucida (cows 72 ) and the oviductal epithelium (sows 76,77 ). As spermatozoa with retroflected flagella swim 'backwards' (head against the direction of travel 78 ), it is equally likely that their passage through mucus or the uterotubal junction is hampered and the oocyte is never reached, as is the case for the c-ros KO mice.…”