Effect of hormone pre-treatment of prepubertal sheep on the production and developmental capacity of oocytes in vitro and in vivo.
Twenty 3-6-week-old Merino lambs were given either 3, 1 or 0 treatments of 50 microg oestradiol benzoate and (48 h later) a 1.5 mg Norgestamet implant left in situ for 9 days (3-, 1- and 0CYCLE+G). On Day 7 after the last implant insertion, and on the same day for 0CYCLE+G, each lamb received 400 I.U. pregnant mare serum gonadotrophin and 6 mg follicle-stimulating hormone (FSH). The reproductive tracts were removed for oocyte collection 24 h after FSH. Reproductive tracts were also collected from 16-24-week-old lambs (n = 31) (0CYCLE-G). The number of antral follicles per ovary was similar for the 3-, 1- and 0CYCLE+G treatments. Similar rates of in vitro maturation and monospermic fertilization were obtained for all groups. The proportion of blastocysts per cleaved oocyte was higher for 1CYCLE+G (50.5%) than for 3CYCLE+G (32.9%), 0CYCLE+G (24.3%), and 0CYCLE-G (11.8%) (P < 0.05). Viable fetuses were obtained at Day 93 of pregnancy after transfer of embryos from all treatments. These results indicate that a single treatment with oestrogen and progesterone, prior to gonadotrophin stimulation, will increase the yield and developmental capacity of oocytes from prepubertal sheep.
O'Brien
J K
JK
Department of Animal Science, University of Sydney, NSW, Australia.
Beck
N F
NF
Maxwell
W M
WM
Evans
G
G
D000818:Animals; D001755:Blastocyst / Q000502:physiology; D004343:Drug Implants; D004624:Embryo Transfer; D004958:Estradiol / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D005307:Fertilization in Vitro; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage / Q000494:pharmacology; D006064:Gonadotropins, Equine / Q000008:administration & dosage / Q000494:pharmacology; D006728:Hormones / Q000008:administration & dosage / Q000494:pharmacology*; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D009929:Organ Size / Q000187:drug effects; D006080:Ovarian Follicle / Q000187:drug effects / Q000502:physiology; D010053:Ovary / Q000254:growth & development; D011247:Pregnancy; D011372:Progestins / Q000008:administration & dosage / Q000494:pharmacology; D012741:Sexual Maturation; D012756:Sheep / Q000254:growth & development*; D014599:Uterus / Q000254:growth & development
D004343:Drug Implants; D006064:Gonadotropins, Equine; D006728:Hormones; D011372:Progestins; C074283:estradiol 3-benzoate; D004958:Estradiol; D005640:Follicle Stimulating Hormone