title: Improved monospermic fertilization and subsequent blastocyst formation of bovine oocytes fertilized in vitro in a medium containing NaCl of decreased concentration.
abstract: The objective of this study was to evaluate whether changes in NaCl concentration in a fertilization medium could improve normal fertilization and preimplantation development of bovine oocytes. In vitro matured bovine oocytes were inseminated with frozen-thawed semen for 18 hr in a Tyrode's medium with albumin, lactate and pyruvate (TALP), to which 114 (TALP-114), 96 (TALP-96) or 78 (TALP-78) mM NaCl was added. Presumptive zygotes were cultured for 192 hr in a modified TALP containing 90 mM NaCl, 1.5 mM glucose, 0.3% (w/v) BSA, minimal essential medium (MEM) essential and nonessential amino acids, and insulin-transferrin-selenium complex. Lower polyspermy rate was obtained by the insemination in TALP-96 (7.8 +/- 2.3%) than by the insemination in TALP-114 (25.6 +/- 1.4%), without decrease in male pronucleus (MPN) formation. Fertilization in TALP-78 also yielded decreased polyspermic fertilization (3.8 +/- 1.5%), but significant decrease in MPN formation was found (63.1 +/- 3.1%). In preimplantation development, more blastocysts developed from oocytes inseminated in TALP-96 (24.1 +/- 1.7%) than from oocytes inseminated in TALP-114 (16.8 +/- 1.4%). TALP-78, however, did not improve preimplantation development beyond the 8-cell stage compared with TALP-114. Mean cell number of blastocyst was higher when oocytes were fertilized in TALP-96 (137.0 +/- 4.5) than in TALP-114 (123.1 +/- 5.1) and in TALP-78 (102.3 +/- 4.5). These results demonstrate that insemination of bovine oocytes in a TALP with decreased NaCl concentration (96 mM) improves blastocyst formation and embryo viability. Decrease in NaCl concentration below 96 mM, however, may delay or inhibit MPN formation, and inhibits subsequent development in vitro.
authors.affiliation: Department of Animal life and Resources, Hankyong National University, Ansung, Korea.
authors.forename: Sangho
authors.initials: S
authors.lastname: Roh
authors.forename: Woosuk
authors.initials: W
authors.lastname: Hwang
authors.forename: Byeongchun
authors.initials: B
authors.lastname: Lee
authors.forename: Jeongmook
authors.initials: J
authors.lastname: Lim
authors.forename: Eunsong
authors.initials: E
authors.lastname: Lee
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000187:drug effects* / Q000502:physiology; D002417:Cattle / Q000196:embryology* / Q000502:physiology; D002467:Cell Nucleus; D002478:Cells, Cultured; D003470:Culture Media; D005260:Female; D005306:Fertilization / Q000187:drug effects; D005307:Fertilization in Vitro / Q000662:veterinary*; D005947:Glucose / Q000494:pharmacology; D019344:Lactic Acid / Q000494:pharmacology; D009865:Oocytes / Q000187:drug effects / Q000254:growth & development*; D019289:Pyruvic Acid / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology*
chemical_list: D003470:Culture Media; D019344:Lactic Acid; D012965:Sodium Chloride; D019289:Pyruvic Acid; D005947:Glucose