Effect of follicle size on cumulus-expansion, in vitro fertilization and development of porcine follicular oocytes
2001
Qian, Y. (Nanjing Medical Univ. (China)) | Shi, W.Q. | Ding, J.T. | Fan, B.Q. | Fukui, Y.
The aim of the present experiment was to investigate the effect of follicular size on oocyte cumulus-expansion, in vitro fertilization and subsequent developmental competence. After maturation culture, the rates of porcine oocytes with expanded cumulus derived from antral follicles >= 5mm, 4 - 4.9mm, 3 - 3.9mm and 2 - 2.9mm in diameter were 90.5%, 89.7%, 85.4% and 67.4%, respectively. After in vitro fertilization, the developmental competence of oocytes dependency increased with follicular size. Higher cleavage rates and higher proportions of 3-4-cell embryos were obtained from >= 4mm follicles compared to 2 - 2.9mm follicles (P<0.05). Although the proportions of 6-8-cell and 12-16-cell embryos obtained from >= 5mm, 4 - 4.9mm, 3 - 3.9mm and 2 - 2.9mm follicles showed no significant differences, embryos obtained from 2 - 2.9mm follicles showed a complete failure to develop beyond the 8-cell stage, embryos obtained from 3 - 3.9mm follicles. failed to develop beyond the 16-cell stage and none of embryos developed beyond the early stage of morula. The percentages of expanded cumulus-oocyte complexes (COCs) and 2-cell cleavage rates of oocytes derived from 2 - 2.9mm follicles were not significantly different when the oocytes were matured for 36h, 42h and 48h in vitro. The exposure to 5% or 15% porcine follicular fluid (PFF) from the large follicles during in vitro maturation (IVM) had no significant effect on the cleavage and subsequent developmental rates of porcine oocytes compared to PFF from small follicles.
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