The Thai Journal of Veterinary Medicine


These experiments were conducted to characterize the follicular oocytes and to assess the oocyte's ability to mature in vitro. The embryo development was evaluated after in vitro fertilization. The follicular oocytes (n = 3015) were graded according to their investments i.e. compact (n 1035), expanded (n 1737), partially denuded (n = 117) and completely denuded (n = 126) as grade 1,2,3 and 4 respectively. The frequencies of embryo development from 2- cell to 32-cell stages in oocytes grade 1 and 2 were statistically significant higher than those in grade 3 and 4 (p < 0.001). The oocytes from grade 3 and 4 failed to develop beyond the 8- cell stage while those from grade 1 and 2 achieved either the morula or blastocyst stage eventhough the percentage of development was low (2-7%). These data demonstrate that immature oocytes from bovine ovary can be matured and fertilized in vitro. The frequencies of embryo development were statistically significant difference between oocytes with cumulus cell and ova without cumulus. The presence of cumulus cells was the obvious indicator of an oocyte's potential to mature, fertilize and develop in vitro.



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