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Ejaculated mouse sperm enter cumulus-oocyte complexes more efficiently in vitro than epididymal sperm.

Li H, Hung PH, Suarez SS - PLoS ONE (2015)

Bottom Line: We compared ejaculated and epididymal sperm in an in vitro fertilization setting to examine whether ejaculated sperm enter cumulus-oocyte complexes more efficiently.At the outset of incubation, ejaculated sperm stuck to the glass surfaces of slides and the incidences of sticking decreased with time; whereas, very few epididymal sperm stuck to glass at any time point, indicating differences in surface charge.We concluded that modification of sperm by male accessory gland secretions affects the behavior of ejaculated sperm, possibly providing them with an advantage over epididymal sperm for reaching the eggs in vivo.

View Article: PubMed Central - PubMed

Affiliation: Family Planning Research Institute, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Wuhan Tongji Reproductive Medicine Hospital, Wuhan, China.

ABSTRACT
The mouse is an established and popular animal model for studying reproductive biology. Epididymal mouse sperm, which lack exposure to secretions of male accessory glands and do not precisely represent ejaculated sperm for the study of sperm functions, have been almost exclusively used in studies. We compared ejaculated and epididymal sperm in an in vitro fertilization setting to examine whether ejaculated sperm enter cumulus-oocyte complexes more efficiently. In order to prepare sperm for fertilization, they were incubated under capacitating conditions. At the outset of incubation, ejaculated sperm stuck to the glass surfaces of slides and the incidences of sticking decreased with time; whereas, very few epididymal sperm stuck to glass at any time point, indicating differences in surface charge. At the end of the capacitating incubation, when sperm were added to cumulus-oocyte complexes, the form of flagellar movement differed dramatically; specifically, ejaculated sperm predominantly exhibited increased bending on one side of the flagellum (a process termed pro-hook hyperactivation), while epididymal sperm equally exhibited increased bending on one or the other side of the flagellum (pro-hook or anti-hook hyperactivation). This indicates that accessory sex gland secretions might have modified Ca2+ signaling activities in sperm, because the two forms of hyperactivation are reported to be triggered by different Ca2+ signaling patterns. Lastly, over time, more ejaculated than epididymal sperm entered the cumulus oocyte complexes. We concluded that modification of sperm by male accessory gland secretions affects the behavior of ejaculated sperm, possibly providing them with an advantage over epididymal sperm for reaching the eggs in vivo.

No MeSH data available.


Related in: MedlinePlus

Western blot analysis of sperm protein tyrosine phosphorylation.Ejaculated and epididymal sperm samples were collected at the beginning (0 h) and after 2 h of incubation under capacitating conditions. Protein lysates equivalent to 2 x 106 sperm were loaded per lane and resolved with an 8% polyacrylamide gel for protein tyrosine phosphorylation detection (p-tyr). β-tubulin was also probed as a loading control.
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pone.0127753.g004: Western blot analysis of sperm protein tyrosine phosphorylation.Ejaculated and epididymal sperm samples were collected at the beginning (0 h) and after 2 h of incubation under capacitating conditions. Protein lysates equivalent to 2 x 106 sperm were loaded per lane and resolved with an 8% polyacrylamide gel for protein tyrosine phosphorylation detection (p-tyr). β-tubulin was also probed as a loading control.

Mentions: To examine whether ejaculated and epididymal sperm responded differently to capacitating conditions, we collected sperm samples at the initiation of capacitation and at 2 h of incubation (the time sperm were added to the COCs) for protein tyrosine phosphorylation analysis. At the beginning of incubation (0 h), ejaculated sperm showed a weak single band of tyrosine-phosphorylated protein between 110 and 130 kDa, while epididymal sperm did not show any visible band (Fig 4). At 2 h incubation under capacitating conditions, both ejaculated and epididymal sperm extracts showed significant increases of protein tyrosine phosphorylation, indicating that both had undergone capacitation to some extent. Nevertheless, more tyrosine-phosphorylated protein bands with higher signal intensity were detected in extracts of ejaculated sperm, suggesting that ejaculated sperm had undergone a higher degree of capacitation than epididymal sperm at the time they were introduced to the COCs.


Ejaculated mouse sperm enter cumulus-oocyte complexes more efficiently in vitro than epididymal sperm.

Li H, Hung PH, Suarez SS - PLoS ONE (2015)

Western blot analysis of sperm protein tyrosine phosphorylation.Ejaculated and epididymal sperm samples were collected at the beginning (0 h) and after 2 h of incubation under capacitating conditions. Protein lysates equivalent to 2 x 106 sperm were loaded per lane and resolved with an 8% polyacrylamide gel for protein tyrosine phosphorylation detection (p-tyr). β-tubulin was also probed as a loading control.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4440731&req=5

pone.0127753.g004: Western blot analysis of sperm protein tyrosine phosphorylation.Ejaculated and epididymal sperm samples were collected at the beginning (0 h) and after 2 h of incubation under capacitating conditions. Protein lysates equivalent to 2 x 106 sperm were loaded per lane and resolved with an 8% polyacrylamide gel for protein tyrosine phosphorylation detection (p-tyr). β-tubulin was also probed as a loading control.
Mentions: To examine whether ejaculated and epididymal sperm responded differently to capacitating conditions, we collected sperm samples at the initiation of capacitation and at 2 h of incubation (the time sperm were added to the COCs) for protein tyrosine phosphorylation analysis. At the beginning of incubation (0 h), ejaculated sperm showed a weak single band of tyrosine-phosphorylated protein between 110 and 130 kDa, while epididymal sperm did not show any visible band (Fig 4). At 2 h incubation under capacitating conditions, both ejaculated and epididymal sperm extracts showed significant increases of protein tyrosine phosphorylation, indicating that both had undergone capacitation to some extent. Nevertheless, more tyrosine-phosphorylated protein bands with higher signal intensity were detected in extracts of ejaculated sperm, suggesting that ejaculated sperm had undergone a higher degree of capacitation than epididymal sperm at the time they were introduced to the COCs.

Bottom Line: We compared ejaculated and epididymal sperm in an in vitro fertilization setting to examine whether ejaculated sperm enter cumulus-oocyte complexes more efficiently.At the outset of incubation, ejaculated sperm stuck to the glass surfaces of slides and the incidences of sticking decreased with time; whereas, very few epididymal sperm stuck to glass at any time point, indicating differences in surface charge.We concluded that modification of sperm by male accessory gland secretions affects the behavior of ejaculated sperm, possibly providing them with an advantage over epididymal sperm for reaching the eggs in vivo.

View Article: PubMed Central - PubMed

Affiliation: Family Planning Research Institute, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Wuhan Tongji Reproductive Medicine Hospital, Wuhan, China.

ABSTRACT
The mouse is an established and popular animal model for studying reproductive biology. Epididymal mouse sperm, which lack exposure to secretions of male accessory glands and do not precisely represent ejaculated sperm for the study of sperm functions, have been almost exclusively used in studies. We compared ejaculated and epididymal sperm in an in vitro fertilization setting to examine whether ejaculated sperm enter cumulus-oocyte complexes more efficiently. In order to prepare sperm for fertilization, they were incubated under capacitating conditions. At the outset of incubation, ejaculated sperm stuck to the glass surfaces of slides and the incidences of sticking decreased with time; whereas, very few epididymal sperm stuck to glass at any time point, indicating differences in surface charge. At the end of the capacitating incubation, when sperm were added to cumulus-oocyte complexes, the form of flagellar movement differed dramatically; specifically, ejaculated sperm predominantly exhibited increased bending on one side of the flagellum (a process termed pro-hook hyperactivation), while epididymal sperm equally exhibited increased bending on one or the other side of the flagellum (pro-hook or anti-hook hyperactivation). This indicates that accessory sex gland secretions might have modified Ca2+ signaling activities in sperm, because the two forms of hyperactivation are reported to be triggered by different Ca2+ signaling patterns. Lastly, over time, more ejaculated than epididymal sperm entered the cumulus oocyte complexes. We concluded that modification of sperm by male accessory gland secretions affects the behavior of ejaculated sperm, possibly providing them with an advantage over epididymal sperm for reaching the eggs in vivo.

No MeSH data available.


Related in: MedlinePlus