STUDIES ON DEVELOPMENT OF GOLDEN HAMSTER EMBRYOS OF EARLY CLEAVAGE STAGES

Four culture media were used to study golden hamster embryo development. These were: TC-199(Ⅰ), TC-199(Ⅱ), Tyrode's solution and Dulbecco's PBS. These media were supplemented with fetal calf serum (FCS), human placental cord serum (HCS) and pregnant golden hamster serum (PHS). The 1-, 2-, 4- and 8-cell stage embryos were recovered from mated female golden hamsters that had been superovulated with pregnant mare's serum and human ehorionic gonadotropin. The developmental rates of 1-cell embryos 24 hr after culture in TC-199(Ⅱ) with 20% PCS or PHS, Tyrode's solution and Dulbecco's PBS with 20% PHS were 89%, 85%, 79% and 77% respectively. When golden hamster embryos were cultured in TC-199 medium with or without pyru-vate and lactate, the former was significantly superior to latter. Similar results were found in Tyrode's medium with 20% PHS or 20% male golden hamster serum. A total of 82- 1-cell embryos were cultured in TC-199(Ⅱ) without serum, none of which had cleaved 24 hr after culture. In an experiment to compare various levels of PHS as a medium supplement, the embryonic development rates in TC-199(Ⅱ) with 20% or 30% PHS and Tyrode's solution with 20% PHS were 86%, 83% and 81% respectively.Thirty-one of eighty-six (36%) 4-cell embryos and fifty-seven of one hundred and thirteen (50%) early 8-cell embryos in various media showed further development after 24 hr of culture. The transfer of 2-cell embryos to recipient golden hamsters resulted in further development! The 2-cell golden hamster embryos survived more than 44 hr, when they were cultured in rabbit oviducts.It was concluded that: (1) Golden hamster serum is an effective component in culture medium for the development of golden hamster embryos in vitro. (2) Pyruvate and laetate used for media supplementation increase significantly the development rate of golden hamster embryos. (3) TC-199, Tyrode's solution and Dulbecco's PBS supplemented with PCS or PHS are satisfactory media for culturing golden hamster embryos. (4) The further development of 4-cell stage embryos have been observed in this study.