This study was carried out to investigate the general characteristics and viability of sperm after freezing and thawing and the pregnancy rates after artificial insemination with thawed semen. The rates of viable sperm after slow and rapid freezing were 87.4±3.85% and 70.8±4.45%, respectively which were significantly lower than that of fresh semen control (91.7±3.45%). The mean concentration of epididymal sperm after dilution in 1.0 ml saline and. 3.0 ml extender in a various concentrations of cryoprotectants was 124.5±48.3 x 10/sup 6/ (range of 45 x 10/sup 6/ to 280 X 10/sup 6/ /ml). There was a significant difference not in the percentage of acrosome-reacted sperm, but in the percentage of capacitated sperm, between fresh and frozen-thawed epididymal semen. When frozen-thawed after diluting with tris-buffer extender containing glycerol, DMSO and ethylene glycol with concentration of 2 to 6%, the rates of epididymal sperm exposed to different cryoprotectants ranged from 14.4±4.7% to 20.7±5.8%, 17.8±5.2% to 36.5±4.9%, and 14.4±4.6% to 18.5±5.3%, respectively which were lower compare to fresh semen control. The pregnancy rate after artificial insemination with frozen semen was 70.6%, whereas that with fresh semen was 90.0% in dogs with naturally induced estrus.

1. The concentrations of Ang. II were 7.20.91 × 10³, 3.80.34 × 10³, 3.50.30 × 10³, 2.80.22 × 10³ pg/ml in bovine follicular fluids from 1∼3 mm, 3∼5 mm, 5∼7 mm and 8∼10 m follicles, respectively. The concentrations of Ang. II decreased in follicular fluids from large follicles. 2. When oocytes were cultured in media containing various concentrations of Ang. II, a higher proportion of oocytes developed to MII stage in medium with 100 ng/ml (79.5%) Ang II compare to that without Ang. II (58.8%). When oocytes from different sizes of follicles were separately cultured in media containing 100 ng/ml Ang. II, maturation rates were higher in oocytes from small and medium follicles those from controls. 3. GSH content in oocytes cultured for 24 hrs in TCM-199 medium containing 10 and 100 ng/ml of Ang. II was also higher than that of oocytes cultured in medium containing 0 or 10 ng/ml Ang. II. When oocytes were cultured in media containing 0, 10, 100, 1,000 ng/ml of Ang. II, the concentrations of GSH were 5.1M, 5.5M, 7.2M, 8.7M, respectively. 4. When oocytes were cultured in media containing various concentrations of 10, 100, 1,000 ng/ml Ang. II, in vitro maturation and developmental rates were 84.0%, 90.0%, 78.0% and 28.0%, 36.0%, 20.0%, respectively. When oocytes were cultured with an addition of Ang. II in media, in vitro maturation rates higher than that of their controls (76.0%).

The study was carried out to investigate the effects of morphology, reproductive cycle, incubation time and activation of oocytes on in vitro maturation of cat oocytes and development of IVM/IVF embryos. The results were summarized as follows: 1. When recovered from ovaries collected at different stages of the reproductive cycle (inactive, follicular and luteal stage), the developmental rates of oocytes to GV and MI stage were 72.5% and 27.5%, 57.5% and 7.5%, 62.5% and 17.5%, respectively. 2. The developmental rates of oocytes with cumulus cells to GV and MI stage in different conditions of incubation (5% CO₂, 95% O₂ and 10% CO₂, 90% O₂) were 70.0% and 27.5%, 52.5% and 20.0%, 55.0% and 12.5%, respectively. 3. The developmental rates to GV and MI oocytes when cultured at different time of incubation (17∼20, 21∼24, 25∼28 and 29∼32 h) were 67.5% and 20.0%, 67.5% and 30.0%, 62.5% and 22.5%, 65.0% and 15.0%, respectively. 4. The fertilization and cleavage rates of freshly collected oocytes with and without cumulus cells were 72.5% and 25.0%, 37.5% and 7.5%, respectively. The rates were greater in oocytes with cumulus cells than those without cumulus cells. 5. The fertilization and cleavage rates of oocytes recovered from ovaries collected at different stages of the reproductive cycle (inactive, follicular and luteal stage) were 75.0% and 25.0%, 40.0% and 7.5%, 50.0% and 15.0%, respectively.

본 연구의 목적은 inbred 마우스 (C57BL/6J)의 수정란을 이용하여 형질전환마우스를 생산할 때, 수정란이식의 효율성을 증진시키기 위한 것이다. C57BL/6J 및 BCF1 마우스로부터 과배란처리 방법에 의해 수정란을 얻고, DNA를 1 세포기 수정란에 미세 주입한 다음, 1세포기 또는 2 세포기의 수정란을 가임신된 마우스의 한쪽 또는 양쪽 난관에 각각 이식하였다. 1세포기의 수정란을 0.75 d.p.c. 가임신된 마우스의 한쪽 난관에 이식했을 때, 임신율이 C57BL/6J는 68.8±7.83%, BCF1은 48.3±14.22% 이었고, 이식한 수정란 당 산자의 발달율은 C57BL/6J가 11.9±5.51%, BCF1은 10.5±8.03%로 성적이 저조하였다. 그러나, 2세포기의 수정란을 0.5 d.p.c. 가임신된 마우스의 양쪽 난관에 이식했을 때, 임신율이 C57BL/6J는 94.4±9.64%, 13CFl은 100±0% 이었고, 이식한 수정란 당 산자의 발달율은 C57BL/6J가 22.1 ±0.4%, BCF1은 21.8±0.38%였다. 따라서 C57BL/6J 마우스의 2세포기 수정란을 0.5 d.p.c. 가임신된 마우스의 양쪽 난관에 이식하는 것이, BCF1마우스와 유사한 성적을 얻어 경쟁력이 있는 것으로 판단되었다. 이러한 결과에 영향을 미치는 인자가 여러 가지 있을 것으로 판단되지만, C57BL/6J 마우스의 2세포기 수정란을 0.5 d.p.c.가임신된 마우스의 양쪽 난관에 이식하는 방법이 다른 방법보다 형질전환마우스를 생산하는데 효율성이 더 높은 것으로 본 실험에서 확인되었다.