Hypotonic resistance of boar spermatozoa: sperm subpopulations and relationship with epididymal maturation and fertility.
Hypotonic resistance of boar spermatozoa was investigated by measuring the ratio of live/dead spermatozoa (SYBR-14/propidium iodide) by flow cytometry after hypotonic stress. The survival rate of ejaculated spermatozoa incubated in hypotonic solutions ranging from 3 to 330 mmol/kg followed a sigmoid curve that fitted a simple logistic model. The critical osmolality value (Osm(crit)) at which 50% of spermatozoa died was determined with this model. Hypotonic resistance of spermatozoa increased with temperature between 15 and 39 degrees C and decreased after hydrogen superoxide treatment, but was not modified during 8 days of preservation in Beltsville thawing solution. Hypotonic resistance markedly decreased during epididymal maturation and after ejaculation as Osm(crit) at 15 degrees C was 54.7+/-3.2, 68.5+/-10.6, 116.7+/-2.1 and 194.3+/-3.7 mmol/kg for the caput, corpus, cauda and ejaculated spermatozoa respectively. Hypo-osmotic stress of 100 mmol/kg revealed a sperm subpopulation exhibiting increased hypotonic resistance compared with the whole ejaculate (Osm(crit)=67.8+/-2.1 mmol/kg). Consistent differences were observed between lean and standard breeds (Pietrain versus Large White) and between boars within the same breed. According to data collected by artificial insemination centers during a large-scale field trial, hypotonic resistance of ejaculates was found to be positively correlated with in vivo fertility.
Druart
Xavier
X
Union Nationale des Coopératives d'Elevage et d'Insémination Animale, Maisons Alfort, France. xavier.druart@tours.inra.fr
Gatti
Jean-Luc
JL
Huet
Sylvie
S
Dacheux
Jean-Louis
JL
Humblot
Patrice
P
D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D015925:Cryopreservation; D004822:Epididymis; D005298:Fertility / Q000502:physiology; D005434:Flow Cytometry / Q000379:methods; D007038:Hypotonic Solutions / Q000494:pharmacology*; D008297:Male; D009994:Osmolar Concentration; D012662:Semen Preservation; D013045:Species Specificity; D013079:Sperm Maturation / Q000187:drug effects; D013094:Spermatozoa / Q000502:physiology*; D013552:Swine / Q000502:physiology*; D013696:Temperature
D007038:Hypotonic Solutions