The present experiments on cryopreservation were designed to examine the effects of solution toxicity, equilibration time and cell stages on the post-thaw survival of bovine IVF embryos. The oocytes were matured in vitro(IVM) for 24 hrs. in TCM-199 supplemented with 35 g /ml FSH, 10 g /ml LH, 1 g /ml estradiol-17 and granulosa cells at 39 under 5% in air. They were fertilized in vitro(IVF) by epididymal spermatozoa treated with heparin for 24 hrs., and then the zygotes were co-cultured in vitro(IVC) with bovine oviductal epithelial cells for 7 to 9 days. The bovine IVF embryos were exposed to the EFS solution in one step at room temperature, kept in the EFS solution during different period for toxicity test, vitrified in liquid nitrogen, and thawed rapidly. 1. after the bovine blastocysts were exposed to EFS solution for 2 min. at room temperature and then they were washed in 0.5 M sucrose solution and TCM-199, they were cultured to examined cryoprotectant induced injury during exposure, Most of the embryos(95.0%) developed to reexpanded blastocoels. However, when the exposure time was extended to 5 and 10 min, these development rates dropped dramatically in 5 min. (69.5%) and 10 min. (47.4%), respectively, 2. When the bovine IVF embryos were vitrified in EFS solution after the equilibration for 1 and 2 min. exposure, The embryos to have reexpanded blastocoels following thawing, washing and culture processes were found to he 82.6 and 73.9%, respectively. However, when the exposure time was extended to 3 min, this survival rate dropped to 18.2%. The optimal time for equilibration of bovine IVF blastocysts in EFS solution seemed to he 1~2 min. 3. When the bovine IVF embryos were equilibrated for 1 min. the significantly (P<0. 05) higher post-thaw survival rates were obtained from the embryos of blastocyst stage(81.3%) than morulae stage(5. 1%). The optimal cell stage for viterification with EFS solution proven to he blastocyst stage in bovine IVF embryos. 4. The number of blastomeres of blastocyst stage was examined with nuclear staining with Hoechst 33342 during 7 to 9 days post-insemination. The cell counts of frozen bovine IVF embryos were found significantly(P7.5 and those of the fresh embryos 76.67. 1, which were cultured in the sarne period and conditions as frozen embryos.

The post-thaw survival of mouse embryos of the various developmental stages was determined after cryopreservation by vitrification in a solution containing ethylene glycol, Ficoll and sucrose (EFS). All the embryos were equilibrated for 2 minutes just prior to freezing. The number of blastomeres during in vitro development was counted by nuclei higher rates of post-thaw survival were obtained from the embryos of 2-cell(92.2%), 8-cell(77.2%) or morula stage(90.0%) than those of blastocyst stage(62.7%). The number of blastomeres per embryo following in vitro culture for 24 hours was significantly(P<0.05) smaller as 66.0f22.3 in vitrified and thawed morulae than fresh morulae(91.712.2).

This study were carried out to investigate the effective concentration of cryoprotective agents and sucrose by one-step straw method, and to determine the optimum thawing temperature and equilibration time of frozen porcine embryos. The porcine embryos foflowing dehydration by cryoprotective agents and a various concentration of sucrose were directly plunged into liquid nitrogen and thawed in 3 water. Survival rate was defined by FDA test. The results are sunnnarized as follows : 1. The survival rates of porcine embryos after ultrarapid frozen4hawing in the freezing medium with a various concentration of glycerol, DMSO and propanediol added 0.25M sucrose were higher survival rate than those of sucrose concentration of 0.50M. 2. The survival rates of porcine embryos after ultrarapid ftozen4hawing in the freezing medium added 0.25M and 0.SOM sucrose were higher survival rate than those of sucrose concentration of 0.75M and 1.00M. 3. The temperature thawed at 2 and 3 resulted in a significantly higher embryos survival rate after 72 hrs in culture than did at 35. 4. The equilibration time on the survival rate of porcine embryos was attained after short period of time(2.5~5 min.) in the freezing medium higher than long period of time(10~20 min.).

The objective of this experiment was to study some possibilities to simplify freezing, thawing and transfer procedure of one-step straw method comparing with the conventional methods using bovine embryos. The previous work are also designed to investigate the thawing effect by development stage and its quality using the embryos. Results obtained were summarized as follows: 1. A total of 87 embryos from 14 donor cows were frozen-thawed and an average of frozen embryo/donor was 6.2. 2. The survival rates of morula stage(65.4%) were higher than those of blastocyst stage(57.l%) and vice versa in rate of morphological recovery (80% vs 95.4%). However. no significant difference was denoted between them. 3. In difference between the groups of good quality and poor quality. good quality was resulted in a significantly higher embryo survival rate(75%) and recovery rates(95%) than poor quality(P<0.0l). 4. In effects of non-permeable sugar dilution in added to l.0M glycerol. higher survival rates were orderd in sucrose. lactose, raffinose and xylose. But lactose-raffinose, sucrose-trehalose and xylose in added to 2.OM glycerol. 5. The highest survival rates were obtained by direct plunge into the liquid nitrogen with 3.OM concentration both of glycerol and trehalose. 6. The survival rates in vitro condition of one-step and direct plunge methods(75%-87.5%) were significantly higher than those of multiple steps (21.4-52.6%) in in vitro (P<0.0l). However, the results of single-step were critical in comparing to other steps of final pregnant conformation.

토양수분함량과 큰검정풍뎅이의 밀도 변화와의 관계를 파악하는데 필요한 기초 자료를 얻기 위해 토양수분함량이 큰 검정풍뎅이의 난과 유충의 생존에 미치는 영향을 조사하였다. 사양토와 식양토의 수분함량 15%와 25%에서는 난과 1, 2, 3령 유충 모두 79% 이상의 생존율을 보였으나 5%와 35%에서는 현저히 떨어졌다. 이 극한 수분함량에서는 토성에 따라 난과 유충의 생존율에 차이가 있는 것으로 보였다. 큰검정풍뎅이의 난은 생존할 수 있는 낮은 수분함량의 한계에 가까워질수록 발육기간이 길어졌다. 식양토에서 33-36%의 높은 수분함량에 난을 일정 기간 처리했을 때 배자 발육을 진행된 난일수록 잘 견뎠고 처리기간이 길어짐에 따라서 전란기간이 길어졌다. 또한 높은 토양수분함량에서는 3령 유충의 섭식 활동이 뚜렷이 억제되었다.

The purpose of this study is to clarify the relation of survival rates of seedling plants under grown orchardgrass populations and control by the difference cutting frequency. The orchardgrass populations investigated in this study have passed for 10 year

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.