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Fertilization and embryo development in sheep and goat oviducts following intra- and inter-specific oocyte transfer
THERIOGENOLOGY
FERTILIZATION AND EMBRYO DEVELOPMENT IN SHEEP AND GOAT OVIDUCTS FOLLOWING INTRA-AND INTER-SPECIFIC OOCYTE TRANSFER Walters, D.L.., Kiehm, D.J., Daniel, S.J. and Armstrong, D.T. MRC Group in Reproductive Biology, Univ. of Western Ont., London, Canada. Oocytes collected from oviducts or preovulatory follicles of 24 FSH-treated donor ewes were transferred, randomly, to oviducts of 12 recipient ewes and 12 recipient nanny goats (does), 52-54 h after synchronization of donors and-recipients by progestagen sponge (Chronoand/or prostaglandin (Estrumate, I.C.I.) gest, Inter-vet) withdraw1 injection. Similar transfers were made from 8 donor does to 4 recipient ewes and 4 recipient does. At the time of oocyte transfer, sheep semen (25-100 x lo6 motile spermatozoa) was deposited in uterine lumina of recipients (ewes or does) of sheep oocytes. Similarly, recipients of goat oocytes were inseminated with goat semen. Recipients' uteri were flushed 2-5 days after transfer to enable assessment of fertilization and embryo development. Mean rates of recovery of the transferred oocytes averaged 60% for sheep ova from sheep uteri and 86% for goat ova from goat uteri, with intermediate recovery rates of 7072% for the xenogenously-transferred ova. Fertilization, assessed as 2-cell embryos to morulae, was as follows: Gamete Donor Species
Fertilization in Sheep Oviducts
Sheep Goat
32/53 6/7
(60%) (86%)
Fertilization in Goat Oviducts 26142 lG/24
(62%) (75%)
Fertilization rates did not differ significantly between the four treatments, indicating similar efficacy of sheep and goat oviducts as sites for fertilization of xenogenous and indiginous oocytes. of species of origin or site of fertWhen oocytes, irrespective ilization, were classified according to site of origin (oviduct or follicle), and whether or not those from follicles had expanded or tight cumulus masses (generally indicative of mature vs immature oocytes, respectively), similar fertilization rates were observed for oviductal (25/31, 81%) and follicular oocytes with expanded cumulus (44/57, 77%). A slightly but not significantly lower fertilization rate of follicular oocytes with tight cumulus (22/37), 59% was observed. The latter included oocytes from three donor ewes and 1 donor doe which proved to be pregnant at the time of oocyte collection. Fertilization rates of oocytes from pregnant donors was slightly lower (6/19, 32%). Following transfer of 26 sheep embryos, half of which resulted from xenogenous fertilization, to uteri of synchronized recipient ewes, 8 pregnancies were established, two of which were from xenogenously-fertilized oocytes. The single pregnancy resulting from 5 transferred goat embryos was from a xenogenously-fertilized oocyte. These results demonstrate thesuitability of the oviducts of sheep and goats as xenogenous sites for completion of maturation of oocytes and capacitation of spermatozoa adequate for fertilization and early embryo development. This may offer an alternative to in vitro capacitation and fertilization techniques for producing successful pregnancies from follicular oocytes of other ruminant species. (Supported by the Medical Research Council and Agriculture Canada).
JANUARY
1986 VOL. 25 NO. 1
211
FERTILIZATION AND EMBRYO DEVELOPMENT IN SHEEP AND GOAT OVIDUCTS FOLLOWING INTRA-AND INTER-SPECIFIC OOCYTE TRANSFER Walters, D.L.., Kiehm, D.J., Daniel, S.J. and Armstrong, D.T. MRC Group in Reproductive Biology, Univ. of Western Ont., London, Canada. Oocytes collected from oviducts or preovulatory follicles of 24 FSH-treated donor ewes were transferred, randomly, to oviducts of 12 recipient ewes and 12 recipient nanny goats (does), 52-54 h after synchronization of donors and-recipients by progestagen sponge (Chronoand/or prostaglandin (Estrumate, I.C.I.) gest, Inter-vet) withdraw1 injection. Similar transfers were made from 8 donor does to 4 recipient ewes and 4 recipient does. At the time of oocyte transfer, sheep semen (25-100 x lo6 motile spermatozoa) was deposited in uterine lumina of recipients (ewes or does) of sheep oocytes. Similarly, recipients of goat oocytes were inseminated with goat semen. Recipients' uteri were flushed 2-5 days after transfer to enable assessment of fertilization and embryo development. Mean rates of recovery of the transferred oocytes averaged 60% for sheep ova from sheep uteri and 86% for goat ova from goat uteri, with intermediate recovery rates of 7072% for the xenogenously-transferred ova. Fertilization, assessed as 2-cell embryos to morulae, was as follows: Gamete Donor Species
Fertilization in Sheep Oviducts
Sheep Goat
32/53 6/7
(60%) (86%)
Fertilization in Goat Oviducts 26142 lG/24
(62%) (75%)
Fertilization rates did not differ significantly between the four treatments, indicating similar efficacy of sheep and goat oviducts as sites for fertilization of xenogenous and indiginous oocytes. of species of origin or site of fertWhen oocytes, irrespective ilization, were classified according to site of origin (oviduct or follicle), and whether or not those from follicles had expanded or tight cumulus masses (generally indicative of mature vs immature oocytes, respectively), similar fertilization rates were observed for oviductal (25/31, 81%) and follicular oocytes with expanded cumulus (44/57, 77%). A slightly but not significantly lower fertilization rate of follicular oocytes with tight cumulus (22/37), 59% was observed. The latter included oocytes from three donor ewes and 1 donor doe which proved to be pregnant at the time of oocyte collection. Fertilization rates of oocytes from pregnant donors was slightly lower (6/19, 32%). Following transfer of 26 sheep embryos, half of which resulted from xenogenous fertilization, to uteri of synchronized recipient ewes, 8 pregnancies were established, two of which were from xenogenously-fertilized oocytes. The single pregnancy resulting from 5 transferred goat embryos was from a xenogenously-fertilized oocyte. These results demonstrate thesuitability of the oviducts of sheep and goats as xenogenous sites for completion of maturation of oocytes and capacitation of spermatozoa adequate for fertilization and early embryo development. This may offer an alternative to in vitro capacitation and fertilization techniques for producing successful pregnancies from follicular oocytes of other ruminant species. (Supported by the Medical Research Council and Agriculture Canada).
JANUARY
1986 VOL. 25 NO. 1
211