Cryopreservation of bull spermatozoa alters the perinuclear theca.
The perinuclear theca (PT) is involved in several important sperm functions leading to fertilization. The objective of this study was to investigate the effect of cryopreservation of bull spermatozoa on the integrity of the PT and the relationship between PT integrity and semen characteristics. Semen from seven bulls was evaluated before and after cryopreservation, comparing the integrity of the plasma membrane (hypo-osmotic test), percentage of live and dead spermatozoa (triple stain), acrosome integrity (triple stain) and the integrity of the PT (negative stain by electron microscopy). Cryopreservation of bull semen caused substantial damage to the PT; the proportion of spermatozoa with a damaged PT was 15.2% versus 52.5% (P<0.05) in fresh versus frozen-thawed spermatozoa, respectively. Furthermore, on average, 67.4% (range, 64-72%) of fresh spermatozoa were live, compared to 53.1% (range, 49-58%) for frozen-thawed spermatozoa; there was an inverse correlation between the percentage of live spermatozoa and the percentage with damage to the PT. Although 59.1% of frozen-thawed spermatozoa had an intact acrosome, only 43.7% of them still remained alive. In frozen-thawed semen, there was a high correlation (r=0.69) between live spermatozoa with an intact acrosome and spermatozoa that maintained an intact PT. In conclusion, freezing/thawing of bull spermatozoa altered the PT and maintaining PT integrity may be necessary to maintain acrosome integrity.
Martínez
Carmen Omega
CO
Departamento de Morfología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, CP 04510 México DF, Mexico.
Juárez-Mosqueda
María de Lourdes
Mde L
Hernández
Jorge
J
Valencia
Javier
J
D000177:Acrosome / Q000502:physiology* / Q000648:ultrastructure; D000818:Animals; D002417:Cattle; D002462:Cell Membrane / Q000502:physiology / Q000648:ultrastructure*; D002467:Cell Nucleus / Q000648:ultrastructure*; D002470:Cell Survival / Q000502:physiology; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary*; D008297:Male; D008854:Microscopy, Electron / Q000662:veterinary; D012661:Semen / Q000166:cytology / Q000502:physiology; D012662:Semen Preservation / Q000009:adverse effects / Q000379:methods / Q000662:veterinary*; D013076:Sperm Count / Q000662:veterinary; D013081:Sperm Motility / Q000502:physiology; D013094:Spermatozoa / Q000502:physiology / Q000648:ultrastructure