This study was conducted to examine the efficiency of enucleation and blastomere isolation from recipient oocytes and donor embryos, respectively and to determine the effect of oocyte age and electric voltage on the fusion rate and in vitro development of the fused oocytes in rabbit nuclear transplantation. Immature oocytes collected from ovarian follicles were matured in vivo for 12 h in TCM-199 containing FCS and hormones and in vivo matured oocytes were collected 17 to 18 h post-HCG. The fresh and frozen donor embryos of 8- to 16-cell stage were collected from the oviduct of superovulated does. The proportion of successfully enucleated oocytes was greatly lower in in vitro matured oocytes (42.3%) than that (62.7%) in in vivo matured oocytes The level of cytochalasin B for in vivo matured oocytes did not affect the efficiency of enuleation, but 7.5 g /mL cytochalasin B for in vitro matured oocytes showed a high enucleation rate significantly. The isolation efficiency of a single blastomere nucleus did not differ between 8- and 16-cell stage embryos. The percentage of single blastomeres isolated from 16-cell stage fresh embryos after 0.5% pronase treatment was greatly higher at 16-min treatment (94.4%) than at 8-min(78. 1%) and the blastomeres(61.5%) isolated from frozen-thawed embryos after 16-min pronase were significantly fewer than those of fresh embryos. The age of recipient oocytes affected nuclear fusion rate. The reconstituted oocytes fused at 24-h age showed slightly higher fusion rate (77.8%) than those (65.0%)fused at 18-h age. The fusion rate of in vitro and in vivo matured oocytes inserted with fresh blastomere did not differ among electric voltages, but the cleavage rate and development to morula-blastocysts of in vitro matured oocytes was more higher under 0.6 kV/cm than under 0.8 to 1.2 kV/cm, while the cleavage rate and development of in vivo matured oocytes was higher under 0.8 to 1.0 kV/cm than under 1.2 kV/cm. The fusion and cleavage rate fol1owing insertion with frozen-thawed blastomere was not different between the in vitro and in vivo matured oocytes and was similar to those from fresh blastomere insertion.

The objective of this study was to produce calves derived from in vitro fertilization of in vitro matured follicular oocytes. Oocytes aspirated from small antral folicles of ovaries obtained at a local slaughter house were matured and fertilized in vitro. At l8hrs after insemination with Korean native cattle semen, oocytes were co-cultured for 6~7 days by utilizing co-culture system with bovine oviduct epithelial cell. After co-culture, good or excellent quality late morulae or early blastocysts were selected by morphological criteria under stereo microscope. Selected embryos were transferred to recipients on day 6 or 7 (estrus = day 0). Recipients were monitored by observation for estrus and rectal palpation after 60 days from embryo transfer. One of them went to term with the birth of a calf. This case is the first production of calf derived from in vitro fertilization in Korea.

Timothy-Orchardgrass우점(優点) 초지(草地)에서 한우(韓牛) 및 교잡우(交雜牛)를 방목축(放牧畜)으로 공시(供試)하여 1980년(年) 6월(月)부터 1982년(年) 10월(月)까지 3년간(年間) 방목(放牧) 방법간(方法間)에 증체량 건물생산량(乾物生産量), 방목습성등(放牧習性等)의 차이(差異)를 검토(檢討)코자 시험(試驗)을 실시(實施)하여 얻어진 결과(結果)는 아래와 같다. 1. ha당(當) 목초건물수량(牧草乾物收量)은 'Wye 대학(

대관령지역에서 달리함에 따른 韓牛育咸牛의 放牧習性과 生産性을 규명하기 爲하여 Wye大學區, 輪換, 固定, 修正固定, 刈取給與區의 處理를 하였다. 供試面積은 5ha, 공시두수는 육성빈우 20두였으며 放牧習性을 調査하기 爲하여 아침 5:00시부터 20:00시 까지 每 2.5분(2분 30초) 마다 調査하여 얻어진 結果는 다음과 같다. 1. ha당 증체량에 있어서 Wye大學區와 輪換區가 바른 처리구보다 많았으나 山地草地放牧方法으로서 實在로 運用하는데는 윤환구나