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Fertilization of rat oocytes is enhanced by FSH during in vitro maturation of oocyte-cumulus complexes
THERIOGENOLOGY
FERTILIZATION OF RAT OOCYTES IS ENHANCED BY FSH DURING IN VITRO MATURATION OF OOCYTE-CUMULUS COMPLEXES X. Zhang and D.T. Armstrong Obstetrics and Gynaecology University of Western Ontario London, Ontario, Canada Cumulus cells previously have been shown to be essential during in vitro maturation (IVM) of rat oocytes, to enable in vitro fertilization (IVF) To investigate the and subsequent normal embryo development. involvement of gonadotropic hormones in regulating this cumulus cell function, oocyte-cumulus complexes (OCC) obtained from follicles of immature (25-day-old) rats without previous hormone treatment were cultured under IVM conditions + FSH (V 001, 100 ng/ml, with FSH potency of 8xNIH-FSH-Sl, and LH potency <.005xNIH-LH-Sl), including one group cultured with FSH + 10e5M aminoglutethimide phosphate (AGP), a cytochrome P450 inhibitor. Positive control OCC, obtained from rats 40 h after treatment in viva with 6 IU PMSG, and an estimated 16 h before the expected preovulatory LH surge, were cultured in similar maturation After lo-12 h of culture in medium without added gonadotropins. maturation medium, oocytes were stripped free of cumulus cells, and assessed for germinal vesicle breakdown (GVB). Steroidogenic response of OCC during IVM was assessed by radioimmunoassay of progesterone in maturation medium. Oocytes with GVB were cultured for an additional 1416 h in IVF medium (J. Reprod. Fert. 77, 401) containing 5~10~ sperm/ml, and examined for fertilization. Fertilized oocytes were cultured for 24 h to enable assessment of cleavage to the two-cell stage. Results are summarized as follows:
In Vivo In Vitro No. of treatment treatment oocytes PMSG none none none
none none FSH FSH+AGP
85 126 105 104
% GVB 90.6a 95.2a 93.3a 90.4a
Fertilization Cleavage rate rate Progesterone (% of GVB) (% of Fert) pg/OCC + SE 72.7a 30.0b 71.4a 23.4b
a5.7a 88.9a a2.9a 90.9a
127 45 116 27
+ 11' +- 5d k 18c + 6d
Values within the same column with different superscripts differ (a vs b, PcO.01; c vs d, P
JANUARY
1989VOL. 31 NO. 1
277
FERTILIZATION OF RAT OOCYTES IS ENHANCED BY FSH DURING IN VITRO MATURATION OF OOCYTE-CUMULUS COMPLEXES X. Zhang and D.T. Armstrong Obstetrics and Gynaecology University of Western Ontario London, Ontario, Canada Cumulus cells previously have been shown to be essential during in vitro maturation (IVM) of rat oocytes, to enable in vitro fertilization (IVF) To investigate the and subsequent normal embryo development. involvement of gonadotropic hormones in regulating this cumulus cell function, oocyte-cumulus complexes (OCC) obtained from follicles of immature (25-day-old) rats without previous hormone treatment were cultured under IVM conditions + FSH (V 001, 100 ng/ml, with FSH potency of 8xNIH-FSH-Sl, and LH potency <.005xNIH-LH-Sl), including one group cultured with FSH + 10e5M aminoglutethimide phosphate (AGP), a cytochrome P450 inhibitor. Positive control OCC, obtained from rats 40 h after treatment in viva with 6 IU PMSG, and an estimated 16 h before the expected preovulatory LH surge, were cultured in similar maturation After lo-12 h of culture in medium without added gonadotropins. maturation medium, oocytes were stripped free of cumulus cells, and assessed for germinal vesicle breakdown (GVB). Steroidogenic response of OCC during IVM was assessed by radioimmunoassay of progesterone in maturation medium. Oocytes with GVB were cultured for an additional 1416 h in IVF medium (J. Reprod. Fert. 77, 401) containing 5~10~ sperm/ml, and examined for fertilization. Fertilized oocytes were cultured for 24 h to enable assessment of cleavage to the two-cell stage. Results are summarized as follows:
In Vivo In Vitro No. of treatment treatment oocytes PMSG none none none
none none FSH FSH+AGP
85 126 105 104
% GVB 90.6a 95.2a 93.3a 90.4a
Fertilization Cleavage rate rate Progesterone (% of GVB) (% of Fert) pg/OCC + SE 72.7a 30.0b 71.4a 23.4b
a5.7a 88.9a a2.9a 90.9a
127 45 116 27
+ 11' +- 5d k 18c + 6d
Values within the same column with different superscripts differ (a vs b, PcO.01; c vs d, P
JANUARY
1989VOL. 31 NO. 1
277