ABSTRACT
The aim of the present study was to investigate the role of progesterone on the developmental competence of cumulus-oocyte complexes [COCs] and cumulus-denuded oocytes [CDOs] at germinal vesicle [GV] stage. GV oocytes of pregnant mare's serum gonadotropin [PMSG]-primed prepubertal mice were divided into two groups: CDOs and COCs. The oocytes were cultured in TCM199 with different concentrations of progesterone [10, 38, 50 and 100 micro M] and without progesterone [controls]. The number of oocytes at the GV, germinal vesicle breakdown [GVBD] and metaphase II [MII] stages were counted. In vitro fertilization [IVF] of MII oocytes and their development to the blastocyst stage were evaluated. Significantly different MII rates were observed between the COCs [85%] and CDOs [68%] control groups. The MII rates of 83%, 48%, 14% and 0% for COCs and 65%, 53%, 20% and 0% for CDOs were obtained in TCM199 that contained 10, 38, 50 and 100 micro M progesterone concentrations, respectively. These MII rates were lower [p<0.05] in both COCs and CDOs as compared to their respective control groups, except for 10 micro M. The fertilization and blastocyst rates of COCs [83% and 35%, respectively] were higher [p <0.05] than those of the CDOs [51% and 5%, respectively] control groups. The fertilization and blastocyst rates in the presence of 10 micro M [81% and 36%, respectively] and 38 micro M [85% and 30%, respectively] progesterone in COCs and CDOs [52% and 4% for 10 micro M; 56% and 4% for 38 micro M] were similar to their respective control groups. Adding progesterone to the medium could not improve maturation of mouse GV oocytes and their development to the blastocyst stage