title: Survival of sheep demi-embryos in vivo and in vitro.
abstract: Sheep embryos (morulae and blastocysts) were bisected either by microscalpel or by microneedle after dissolving the zona pellucida with acidified Tyrode's solution. Fourteen and 11 cryopreserved demi-embryos failed to develop when transferred to recipients or placed in culture, respectively. When fresh demi-embryos were cultured in Dulbecco's phosphate buffered saline (DPBS) plus fetal calf serum (FCS) or Whitten's medium, the survival rate was 26% compared to 68% for whole embryos (P<0.01), and there was a suggestion that the presence of a zona pellucida was beneficial to survival. When two demi-embryos each within a zona pellucida were transferred into each of 10 ewes, six of them lambed to produce a total of eight lambs, including two sets of identical twins. Of 10 ewes receiving two demi-embryos without zonae pellucidae, three lambed to produce a total of four lambs, including one set of identical twins. Of 10 ewes that each received two whole embryos, 10 lambed to produce a total of 16 lambs. There was a suggestion that the zona pellucida might enhance the survival of demi-morulae but not demi-blastocysts.
authors.affiliation: Department of Immunology, John Curtin School of Medical Research, Australian National University, Canberra, Australia.
authors.forename: J N
authors.initials: JN
authors.lastname: Shelton
authors.forename: A
authors.initials: A
authors.lastname: Szell