These experiments were carried out to determine the effect of pregnancy in bisected embryo. The embryos of ICR mouse were microsurgically bisected at morula and blastocyst stage using microsurgical blade attached a micromanipulator. These bisected embryos without zona pellucida were cultured up to blastocyst stage and cell count and diameter of stained blastomere, and transferred pseudopregnant mice. And the development of these bisected embryos was compared with the results of production of young of the corresponding intact embryos or cell stage. When the bisected mouse embryos were cultured in vitro for 20 to 24 hours in morula stage(77.2%) or 3 to 6 hours in blastocyst stage(84.1%), them were developed to the expanded blastocyst stage. There were no significant(P<0.05) differences in the development rate of bisected embryos between in morula and blastocyst stages. The embryo size of blastocyst developed in vitro from bisected embryo was small(P<0.05)than intact embryo. However, the number of blastomeres with bisected embryo (24.7+1.3and 21.5+1.2 respectively) were significantly(P<0.05) reduced, compared with that of intacted embryos(36.3+1.1 and 41.4+1.2 respectively). When compared with the result of pregnancy rate(63.6%) after surgical transfer of bisected morulae, a similar result(65.4%) was obtained with bisected blastocyst stage(P< 0.05). However, production of youngs (38.8%) after transfer of bisected morula, a similar result (38.1%) was obtained with bisected blastocyst stage (P<0.05).

가축의 일란성 쌍태를 생산하기 위한 기술 개발을 확립하고자 상실배 및 포배기에 있는 BALB/c 계통의 생쥐 수정란을 micromanipulator로 분할 수정란을 작출하고 이를 체외배양을 실시하여 발달성적을 조사하였으며, 외과적 및 비외과적 이식을 실시하여 착상율 및 산자생산 성적을 조사한 결과는 다음과 같다. 1. 상실배 및 포기배에 있는 총 811개의 정상적인 수정란을 분할하여 이중에서 666(82.1%)개가 분할시의 물리적인 손상이 없이 분할되었

The effects of cryoprotectants (glycerol, DMSO and ethylene glycol) and the concentrations (0, 0, 25, 0.5and 1.0 M) of sucrose in the diluent on the is vitro survival of mouse morulae froaen rapidly in liquid nitrogenvapour were examined. When the embryos were equilibrated in 1.5 M cryoprotectants +0.25 M sucrose in one-step or in 3.0 M cryoprotectants +0.25 sucrose in two-step and diluted with 0, 0.25, 0.5, or 1.0 M sucrose solution after thawing, high survival rates were obtained in ethylene glycol (48.0% to 88.2 %) or in glycerol (35.0 % to 77.8 %). These results show that 1.5 M ethylene glycol is a highly efficient cryoprotective agent for the rapid freezing of mouse morula embryos and 0.5 M sucrose was optimal concentration in the diluent after thawing.