title: Effects of temperature gradients on in vitro maturation of bovine oocytes.
abstract: The effect of temperature gradients on in vitro maturation of bovine oocytes was examined in this study. Six treatment groups were made by combining 3 different maturation periods (0 to 10 h, 10 to 18 h and 18 to 24 h) with 2 different culture temperatures (37.0 degrees C and 38.5 degrees C). The frequency of oocytes matured to the metaphase II stage was apparently gradually increased as the culture temperature was increased from 37.0 degrees C to 38.5 degrees C at 0, 10 and 18 h after the onset of culture (75.2 vs 80.5, 82.3 and 84.3%, respectively), but this difference was not significant. Neither was the minor decrease in the proportion of oocytes reaching metaphase II when the temperature was decreased from 38.5 degrees C to 37.0 degrees C at 10 and at 18 h after the onset of maturation (84.3 vs 82.4 and 78.0%, respectively). However, more oocytes cleaved (79.2%; P = 0.0653) and developed to morulae (43.6%; P = 0.0019) and blastocysts (27.4%; P = 0.1568) when they were in vitro matured at 38.5 degrees C between 0 and 10 h, and then at 37.0 degrees C from 10 to 24 h. Although only the morula group was statistically different, cleavage- (79.2 vs 69.8, 72.5, 74.2, 76.3, 74.3%, respectively) and blastocyst formation (27.4 vs 23.2, 24.6, 25.2, 19.6, 21.9%, respectively) from this group was the highest among the 6 treatments.
authors.affiliation: Animal Reproduction Laboratory, Guangxi University, Nanning, P.R. China.
authors.forename: D S
authors.initials: DS
authors.lastname: Shi
authors.forename: B
authors.initials: B
authors.lastname: Avery
authors.forename: T
authors.initials: T
authors.lastname: Greve
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000502:physiology; D002417:Cattle / Q000502:physiology*; D002467:Cell Nucleus / Q000502:physiology; D002478:Cells, Cultured; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D008540:Meiosis; D008677:Metaphase; D009028:Morula / Q000502:physiology; D009865:Oocytes / Q000502:physiology* / Q000648:ultrastructure; D013696:Temperature