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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

CASA analysis of ejaculated (diamond) and epididymal (rectangle) mouse sperm.Sperm samples were collected every hour during capacitation. Data are presented as mean ± SD (N = 5). Asterisks indicate significant difference (P < 0.05) between ejaculated and epididymal sperm, determined by paired t-test.
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pone.0127753.g003: CASA analysis of ejaculated (diamond) and epididymal (rectangle) mouse sperm.Sperm samples were collected every hour during capacitation. Data are presented as mean ± SD (N = 5). Asterisks indicate significant difference (P < 0.05) between ejaculated and epididymal sperm, determined by paired t-test.

Mentions: To eliminate the contribution of individual animal to variation, we compared ejaculated and epididymal sperm from the same male collected on different days (ejaculated sperm and then the epididymal sperm 2–7 days later, N = 5). At the initiation of incubation under capacitating conditions, more ejaculated sperm were motile than epididymal sperm (80.4 ± 7.0% and 69.6 ± 6.0% for ejaculated and epididymal sperm, respectively; P = 0.035, N = 5). In samples taken at the beginning of incubation under capacitating conditions, ejaculated sperm had higher VSL, STR, and LIN than epididymal sperm (Fig 3). At 3 h of incubation under capacitating conditions, the ejaculated sperm still had higher VSL and STR than the epididymal sperm (Fig 3), even though about 60% of the epididymal sperm had lost the cytoplasmic droplet by that time.


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

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

CASA analysis of ejaculated (diamond) and epididymal (rectangle) mouse sperm.Sperm samples were collected every hour during capacitation. Data are presented as mean ± SD (N = 5). Asterisks indicate significant difference (P < 0.05) between ejaculated and epididymal sperm, determined by paired t-test.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0127753.g003: CASA analysis of ejaculated (diamond) and epididymal (rectangle) mouse sperm.Sperm samples were collected every hour during capacitation. Data are presented as mean ± SD (N = 5). Asterisks indicate significant difference (P < 0.05) between ejaculated and epididymal sperm, determined by paired t-test.
Mentions: To eliminate the contribution of individual animal to variation, we compared ejaculated and epididymal sperm from the same male collected on different days (ejaculated sperm and then the epididymal sperm 2–7 days later, N = 5). At the initiation of incubation under capacitating conditions, more ejaculated sperm were motile than epididymal sperm (80.4 ± 7.0% and 69.6 ± 6.0% for ejaculated and epididymal sperm, respectively; P = 0.035, N = 5). In samples taken at the beginning of incubation under capacitating conditions, ejaculated sperm had higher VSL, STR, and LIN than epididymal sperm (Fig 3). At 3 h of incubation under capacitating conditions, the ejaculated sperm still had higher VSL and STR than the epididymal sperm (Fig 3), even though about 60% of the epididymal sperm had lost the cytoplasmic droplet by that time.

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