Abstract:RESUMOAvaliou-se o efeito do diâmetro e da fase do desenvolvimento folicular sobre a competência de oócitos para a produção in vitro de embriões bovinos. A primeira onda folicular foi sincronizada com progestógeno por nove dias e 24 horas após a sua retirada aplicou-se LH. Os ovários foram recuperados 60h (G-60), 96h (G-96) e 108h (G-108) após a ovulação induzida pelo LH. Os folículos foram dissecados ou aspirados e medidos e os oócitos recuperados e submetidos à maturação, fecundação e cultivo in vitro. Os ov… Show more
“…The low rate of good quality COCs from small follicles is probably due to their higher incidence of follicular atresia compared with large follicles. Indeed, at the moment of follicular aspiration and independent of the estral cycle phase, more than 85% of ovarian follicles are atretic (Castilho et al, 2007).…”
Oocyte quality is one of the most important aspects of in vitro embryo development. Extensive epigenetic programming must occur during oocyte growth and maturation. A specific DNA methylation pattern of the imprinted genes must be established on differentially methylated regions (DMR). The insulin-like growth factor 2 (IGF2) gene is an important growth factor, and it is imprinted in several mammalian species. The aim of this study was to evaluate the methylation pattern on the DMR of the last exon of IGF2 in immature and mature bovine oocytes with different developmental competencies. Mature oocytes from large follicles were less methylated (28.93%) than immature oocytes from large follicles (77.38% P = 0.002), and there was also a tendency towards lower methylation in mature oocytes from large follicles (28.93%) compared with mature oocytes from small follicles (52.58% P = 0.07). Immature oocytes from small and large follicles showed 53.85% (7/13) and 91.66% (11/12) hypermethylated sequences, respectively, whereas mature oocytes from small and large follicles showed 61.11% (11/18) and 40% (4/10), respectively. The hypomethylation pattern in mature oocytes from large follicles may be related to the higher competence of these oocytes. Our results suggest that the methylation pattern in this DMR may be a useful parameter to investigate as a molecular marker for oocyte competence in cattle and as a model for studies in other species.
“…The low rate of good quality COCs from small follicles is probably due to their higher incidence of follicular atresia compared with large follicles. Indeed, at the moment of follicular aspiration and independent of the estral cycle phase, more than 85% of ovarian follicles are atretic (Castilho et al, 2007).…”
Oocyte quality is one of the most important aspects of in vitro embryo development. Extensive epigenetic programming must occur during oocyte growth and maturation. A specific DNA methylation pattern of the imprinted genes must be established on differentially methylated regions (DMR). The insulin-like growth factor 2 (IGF2) gene is an important growth factor, and it is imprinted in several mammalian species. The aim of this study was to evaluate the methylation pattern on the DMR of the last exon of IGF2 in immature and mature bovine oocytes with different developmental competencies. Mature oocytes from large follicles were less methylated (28.93%) than immature oocytes from large follicles (77.38% P = 0.002), and there was also a tendency towards lower methylation in mature oocytes from large follicles (28.93%) compared with mature oocytes from small follicles (52.58% P = 0.07). Immature oocytes from small and large follicles showed 53.85% (7/13) and 91.66% (11/12) hypermethylated sequences, respectively, whereas mature oocytes from small and large follicles showed 61.11% (11/18) and 40% (4/10), respectively. The hypomethylation pattern in mature oocytes from large follicles may be related to the higher competence of these oocytes. Our results suggest that the methylation pattern in this DMR may be a useful parameter to investigate as a molecular marker for oocyte competence in cattle and as a model for studies in other species.
“…RAUBER et al (2003) citaram que, provavelmente, as substâncias estimuladoras estejam presentes nos folículos grandes e médios e ausentes ou presentes em menor concentração em folículos pequenos. Já CASTILhO et al (2007), estudando o diâmetro e a fase de desenvolvimento folicular em bovinos da raça Nelore, concluíram que o desenvolvimento folicular influencia a competência oocitária para o desenvolvimento in vitro, observando que, nos estádios iniciais da onda folicular, a produção de blastocisto foi maior em oócitos de folículos pequenos e, com o avanço da onda, a produção de blastocistos foi maior em oócitos obtidos de folículos maiores. FIGUEIREDO et al (1997) concluíram que, além do fator individual, outro aspecto de ordem biológica a ser considerado como possível variável na FIv é a interação folículo-oócito.…”
“…The in vitro procedures, IVM (in vitro maturation), IVF (in vitro fertilization), and IVC (in vitro cultivation), were performed according to Castilho et al (2007) adapted by the analyzed laboratory.…”
Variability in the production of bovine blastocysts per session of ultrasound-guided follicularaspiration(OPU) is still an obstacle in commercial production.Thus, the objective of the current work was to verify factors that influence in vitro embryo production (PIVE), using data from a commercial laboratory.Data from 2014 to 2016 were analyzed, referring to 799 OPU sessions of adult bovine females of the breeds: Nelore (n=83), Girolando (n=73), Brangus (n=49), HPB (n=20), and Senepol (n=10).The influence of five variables was analyzed: breed, genetic group, frequency of aspiration, type of semen (sexed/conventional), and seasonality (spring/summer vs. autumn/winter) on the rate of viable oocytes, cleavage, and blastocyst production (bl).The protocols for the in vitroproduction of embryos (IVP) followed the routine established by the partner laboratory of the present study. The statistical analysis of the data was performed using SAS, with the Chi-square test.The Girolando and Nelore breeds had a higher (p=0.0001) number of blastocysts/OPU session, as well as the Bos indicus blood group.Blastocyst production was higher (p=0.0059) with sexed semen compared to conventional semen (6.6 x 5.2 bl/OPU session); a higher frequency of aspirations also increased (p=0.005) the number of bl/OPU session (7.7 x 5.9).We conclude that the in vitro production of bovine embryos is influenced by the analyzed factors and knowledge of these variables could guide the commercial use of OPU-PIVE.
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