title: Effect of superstimulation protocols on nuclear maturation and distribution of lipid droplets in bovine oocytes.
abstract: Our objective was to study the effect of superstimulation protocols on nuclear maturation of the oocyte and the distribution of lipid droplets in the ooplasm. Heifers (n=4 each group) during the luteal phase were either treated with FSH for 4 days (Short FSH), FSH for 4 days followed by 84h of gonadotropin free period (FSH Starvation) or for 7 days (Long FSH) starting from the day of wave emergence. In all groups, LH was given 24h after induced luteolysis (penultimate day of FSH) and cumulus-oocyte complexes were collected 24h later. Oocytes were stained for nuclear maturation (Lamin/chromatin) and lipid droplets (Nile red). The Long FSH group had a greater proportion of mature oocytes (metaphase II) compared with heifers in the Short FSH and FSH Starvation groups (59/100 vs 5/23 and 2/25, respectively; P<0.01). On average across all groups, oocytes contained 22pL of lipids (3.3% of ooplasm volume) distributed as 3000 droplets. Average volume of individual lipid droplets was higher in the FSH Starvation (11.5±1.5 10(-3) pL, P=0.03) compared with the Short and Long FSH groups (7.2±0.6 10(-3) and 8.0±0.8 10(-3) pL, respectively). In conclusion, both FSH Starvation and Short FSH treatments yielded a lower proportion of mature oocytes compared with the Long FSH treatment. Furthermore, FSH starvation led to an accumulation of larger lipid droplets in the ooplasm, indicating atresia. Our results indicate that a longer superstimulation period in beef cattle yields higher numbers and better-quality oocytes.
authors.affiliation: Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada.
authors.forename: D
authors.initials: D
authors.lastname: Dadarwal
authors.affiliation: Department of Animal Reproduction, Gynaecology and Obstetrics, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, Punjab, India.
authors.forename: M
authors.initials: M
authors.lastname: Honparkhe
authors.affiliation: Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada.
authors.forename: F C F
authors.initials: FC
authors.lastname: Dias
authors.affiliation: Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada.
authors.forename: T
authors.initials: T
authors.lastname: Alce
authors.affiliation: Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Lessard
authors.affiliation: Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Singh
mesh_terms: D000818:Animals; D002417:Cattle; D002467:Cell Nucleus / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D066292:Lipid Droplets / Q000187:drug effects / Q000502:physiology*; D007986:Luteinizing Hormone / Q000494:pharmacology; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D010062:Ovulation Induction / Q000379:methods / Q000662:veterinary*; D013480:Superovulation / Q000187:drug effects / Q000502:physiology*
chemical_list: D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone