title: Effect of Follicle Size on In Vitro Maturation of Pre-Pubertal Porcine Cumulus Oocyte Complexes.
abstract: Very small follicles (<3.0 mm diameter) are over-represented on the surface of ovaries of non-cycling pigs, and the oocytes collected from these follicles generally have reduced developmental competence in vitro. This study examined the effect of follicle size on the nuclear maturation (n = 608), the potential of parthenogenetic activation (n = 243) and the cyclic AMP (cAMP) content of pre-pubertal porcine oocytes (n = 480). In addition, the influence of follicle size on steroid hormone synthesis was analysed. Cumulus oocyte complexes (COCs) flushed from small (2.5-4.0 mm) or large (4.5-6.0 mm) ovarian follicles were cultured for 0, 28 and 46 h. After 46 h of IVM, a greater proportion of oocytes from 4.5- to 6.0-mm follicles reach metaphase II (MII) compared with those from follicles with 2.5-4.0 mm of diameter (96.1 vs 77.0%, respectively; p < 0.001). Parthenogenetic activation of oocytes from large follicles produced higher developmental rates than oocytes from large follicles (p < 0.05). At 28 h, the IVM medium with oocytes from large follicles contained significantly more 17ß-oestradiol (E2 ) than the medium with oocytes from small follicles (5.55 vs 3.45 ng/ml, respectively; p < 0.05) and at 46 h, the medium with oocytes from small follicles contained significantly more progesterone (P4 ) than the medium with oocytes from large follicles (276.7 vs 108.2 ng/ml, respectively, p < 0.05). Porcine oocytes from large follicles have higher nuclear and cytoplasmic maturation capacities, but the differences did not appear to be cAMP-mediated. Our findings also suggest that COCs from small follicles undergo more intensive luteinization than COCs from large follicles. The results show that oocytes from follicles with a diameter greater than 4.0 mm are more suitable for in vitro studies.
authors.affiliation: Department of Reproductive Biology, University of Veterinary Medicine Hannover Foundation, Hannover, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Töpfer
authors.affiliation: Department of Reproductive Biology, University of Veterinary Medicine Hannover Foundation, Hannover, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Ebeling
authors.affiliation: Unit of Reproductive Biology, Leibniz Institute for Farm Animal Biology (FBN), Dummerstorf, Germany.
authors.forename: J M
authors.initials: JM
authors.lastname: Weitzel
authors.affiliation: Department of Reproductive Biology, University of Veterinary Medicine Hannover Foundation, Hannover, Germany.
authors.forename: A C
authors.initials: AC
authors.lastname: Spannbrucker
mesh_terms: D015096:3-Hydroxysteroid Dehydrogenases / Q000235:genetics; D000818:Animals; D002467:Cell Nucleus / Q000502:physiology; D054885:Cumulus Cells / Q000502:physiology*; D000242:Cyclic AMP / Q000032:analysis; D003593:Cytoplasm / Q000502:physiology; D004958:Estradiol / Q000032:analysis / Q000378:metabolism; D005260:Female; D059471:In Vitro Oocyte Maturation Techniques / Q000662:veterinary*; D009865:Oocytes / Q000502:physiology* / Q000648:ultrastructure; D009929:Organ Size; D006080:Ovarian Follicle / Q000033:anatomy & histology* / Q000737:chemistry; D010312:Parthenogenesis; D011374:Progesterone / Q000032:analysis / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D011974:Receptors, LH / Q000235:genetics; D034421:Sus scrofa
chemical_list: D012333:RNA, Messenger; D011974:Receptors, LH; D011374:Progesterone; D004958:Estradiol; D000242:Cyclic AMP; D015096:3-Hydroxysteroid Dehydrogenases