• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.1
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• pp.38-43
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• 2003

Immature and mature embryos of 18 Korean wheat genotypes were cultured in vitro to develop an efficient method of callus formation and plant regeneration, and to compare the responses of both embryo cultures. Immature and mature embryos were placed on a solid agar medium containing the MS salts and vitamins, 30g/l maltose, 2 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D), and amino acids. The developed calli were maintained on regeneration medium containing MS salts and B5 vitamins, 20 g/l sucrose, and the combination of two plant growth regulators, 6-benzylaminopurine (BAP) and indole-3-acetic acid (IAA). Immature embryos in most genotypes showed high efficiency of callus induction except three genotypes; Eunpamil, Chunggemil, and Namhaemil, and significant differences among the genotypes. Plant regeneration of calli induced from immature embryos showed high efficiency in Geurumil (56.5%), Tapdongmil (50.5%), Gobunmil (45.5%), and Urimil(42.2%). The analysis of variance showed significant differences for regeneration frequency among the genotypes. Mature embryos showed low callus induction frequency compared with that in immature embryos, and significant differences among the genotypes. Plant regeneration of calli induced from mature embryos showed high efficiency in Keumkangmil (33.33%), Tapdongmil(28.13%), and Geurumil (27.78%). The analysis of variance showed significant differences for plant regeneration frequency among the genotypes.

• Journal of Plant Biology
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• v.37 no.3
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• pp.333-341
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• 1994

Effective plant regeneration from immature cotyledons of soybean [Glycine max (L.) Merr.] cultivars was achieved via somatic embryogenesis. Somatic embryogenesis was performed with the cotyledons of immature embryos 14-20 d after flowering. Immature cotyledons of cv. Whangkeum were placed abaxial or adaxial side down on modified MS medium containing 20mg/L 2,4-D. The greatest number of somatic embryos, 1.2 per cotyledon, was produced from those of 4.0-4.9 mm in length which had been placed abaxial side down. Among cvs. Pecking, Whangkeum and Baekwoon, Pecking had the highest embryo induction efficiency with 4.3 somatic embryos per cotyledon in 20mg/L 2,4-D treatment and with 1.0 embryo per cotyledon in 8mg/L NAA treatment. Germinable globular somatic embryos were induced with the highest efficiency, 27.6%, in 20mg/L 2,4-D and were proliferated efficiently on liquid medium containing 10mg/L 2,4-D. The globular somatic embryos developed into germinable mature somatic embryos on medium containing 10 $\mu$M CoCl2, 9% sucrose, and 0.5% activated charcoal. These mature somatic embryos germinated on hormone-free mediu. After transfer to the soil, regenerated plants with seeds were obtained.

• Korean Journal of Animal Reproduction
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• v.18 no.1
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• pp.25-29
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• 1994

This study was carried out to investigate the in-vitro fertilization rate survival rate of rapidly frozen porcine immature embryos. The porcine embryos following dehydration by cryoprotectants containing sucrose were directly plunged into liquid nitrogen and thawed in 3$0^{\circ}C$ water bath. Survival rate was defined as development rate on vitro culture or FDA test. The results are summarized as follows : 1. The in vitro fertilization rate of all frozen immature oocytes(6.7~26.7%) was very low, 35.0% of unfrozen oocytes and the rate of immature oocytes was very higher than that of mature oocytes. 2. The survival rate of all frozen immature oocytes(10.3~25.0%, 13.3~30.0%) was very low, 45% of unfrozen oocytes and the rate of immature oocytes was slightly higher than that of mature oocytes.

• Journal of Life Science
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• v.11 no.4
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• pp.311-315
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• 2001

To identify the effects embryo developmental stage and gelrite concentration on plant regeneration in seed culture of rice, mature and immature seeds of rice were cultured on the $N_{6}$ medium supplemented with2 mg/$\ell$ 2.4-D and different levels of gelrite(0.2~1.0%). The calli formed immature embryos were produced more plants than those from mature embryos. The maximum frequency of plant regeneration was achieved in the culture of the calli of immature embryos which was harvested at the 21$^{th}$ day after pollination. The plant regeneration on the medium with gelrite was more accelerate than that on the medium with agar. The highest frequency(55%) of plant regeneration was obtained from the calli transferred to the medium with 6g/$\ell$ gelrite.

• Journal of Life Science
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• v.19 no.12
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• pp.1764-1768
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• 2009

This study was carried out to examine a concentration of steroid hormones and in vitro development of mouse embryos in culture supernatant of bovine granulosa cells (GC). To obtain the culture supernatant, granulosa cells were retrieved from mature follicles (6~15 mm diameter) and immature follicles (2~5 mm diameter) of bovine ovary and were cultured, respectively, in media of Ham's F-10 with 15% FCS for 16 days. Mature and immature granulosa cells formed their monolayers easily and showed similar growth patterns in culturing. There was no morphological difference between mature and immature granulosa cells. High levels of both progesterone and estradiol were detected in the culture supernatant of mature granulosa cells and immature granulsa cells, and the endocrine profiles of the two types of cells were similar. Progesterone secretion of granulosa cells was high in the late stage of culturing and estradiol secretion was high in the early stage of culturing. In vitro development rates of mouse embryos to morula, blastocyst and hatched blastocyst were significantly (p<0.05) higher in culture supernatant of mature granulosa cells (92.7%, 78.1% and 34.5%) and in culture supernatant of immature granulosa cells (96.4%, 78.5% and 26.8%) than in Ham's F-10 (86.7%, 41,7% and 13.3%). However, there was no difference between the culture supernatant of mature granulosa cells and the culture supernatant of immature granulosa cells in the development of embryos.

• Journal of Embryo Transfer
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• v.26 no.3
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• pp.201-207
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• 2011

The present study was performed to investigate the survival and subsequent embryonic developmental rate of immature and mature oocytes after vitrification and pronuclear stage embryos after slow-freezing and vitrification. We have also tried to examine the dependency of concentrations (7.5, 15%) and exposure time (5, 10, 20 min) of ED cryoprotectant on developmental rate of pronuclear stage embryos. The developmental rates of 2-ce1l and blastocyst embryos at mature oocytes were significantly (p<0.05) higher than immature oocytes. After slow freezing, vitrification and thawing of pronuclear stage embryo, the survival and developmental rates of blastocysts and hatched blastocysts were significantly (p<0.05) higher after vitrification than after slow-freezing. On contrary, the developmental rates of 2-cell embryos were significantly (p<0.05) higher after slow freezing than after vitrification. The cryopreservation methods of pronuclear stage embryos vitrified by exposed to 7.5% ED solution for 5 minutes was significantly (p<0.05) higher than other experimental group. The results of our study suggest 1hat the developmental rates of mature oocytes have been more successful than immature oocytes during vitrification. Vitrification was more efficient than slow freezing in case of pronuclear stage embryos. The effective cryopreservation method of pronuclear stage embryos was vitrified by exposed to 7.5% ED solution for 5 minutes.

• Korean Journal of Animal Reproduction
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• v.21 no.4
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• pp.355-362
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• 1997

This study was undertaken in an effort to product embryos through in vitro maturation(IVM), in vitro fertilization(IVF) and in vitro culture(IVC) after cryopreservation of immature and mature porcine oocytes. The experiments were conducted to investigate IVM rate of oocytes frozen with 3 different cryoprotectants and to examine IVF and IVC of frozen-thawed oocytes. The CEI(cumulus cells expansion index) after IVM of frozen-thawed immature oocytes was higher in oocytes frozen with PG＋PEG(propylene glycol plus polyethylene glycol) than those frozen with single cryoprotectant and this index was almost 90% of unfrozen oocyte's index(2.39 vs. 2.66). The IVF rate of all frozen oocytes was very low(68% of unfrozen oocytes) and the IVF rate of frozen immature oocytes was slightly higher than that of frozen mature oocytes(39.0% vs. 34.4%), but polyspermic penetration was higher in frozen immature oocytes(21.9% vs. 19.1%). The cleavage rate after IVF of frozen-thawed oocytes was 9.3% for frozen mature oocytes and 11.3% for frozen immature oocytes and this rate was significantly lower(P<0.05) than that of control(60.7%). The development to 8-cell stage was greatly lower in frozen mature oocytes than in frozen immature oocytes. The results indicate that the use of PG plus PEG as cryoprotectant may be very effective for vitrification of porcine oocytes and the frozen-thawed immature porcine oocytes can be used fro in vitro embryo production based on IVM, IVF and IVC system.

• Journal of Plant Biology
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• v.37 no.3
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• pp.365-370
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• 1994

Excised cotyledon segments of ginseng zygotic embryos at various developmental stages were cultured on MS basal medium from which somatic embryos were directly induced. The frequency of somatic embryo formation on the segments declined with the advancing zygotic embryo maturity. All of the cells in the cotyledons of immature zygotic embryos were smaller and more densely cytoplasmic than those in mature embryos. Histological examinations revealed that the poly-somatic embryos formed on immature embryos were of multi-cell originand derived from the epidermal and subepidermal cell layers. However, in the cotyledon of germinating zygotic embryos, only theepidermal cells were densely cytoplasmic and singularly competent to develop into somatic embryos resulting into single embryos at a frequency of 100%.

• Clinical and Experimental Reproductive Medicine
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• v.42 no.3
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• pp.118-125
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• 2015

Objective: The goal of this study was to evaluate the pregnancy potential of immature (metaphase I or germinal vesicle stage) oocytes retrieved in intracytoplasmic sperm injection (ICSI) cycles. Methods: A total of 1,871 couples with infertility underwent 2,984 ICSI cycles. Cycles in which three or fewer oocytes were retrieved were included in this study in order to evaluate the pregnancy potential of immature oocytes. Cycles were divided into five groups (group I-V), according to the maturation status of the oocytes at the time of cumulus cell removal and ICSI. The fertilization and pregnancy rates after ICSI were analyzed and compared among the study groups based on the maturation status of the retrieved oocytes. Results: The retrieval of only immature oocytes was associated with a significant decrease in the fertilization rate ($76.1%{\pm}37.3%$ vs. $49.0%{\pm}49.1%$, $66.7%{\pm}48.7%$; group I vs. group II, group III, respectively) and the average number of transferred embryos ($1.5{\pm}0.7$ vs. $1.1{\pm}0.4$, $1.1{\pm}0.6$). The cycle cancellation rate was significantly higher when only immature oocytes were retrieved. The clinical pregnancy rate decreased significantly when the transferred embryos had originated from immature oocytes (16.9% vs. 10.3%, 1.2%). Conclusion: In ICSI cycles, the fertilization potential and pregnancy potential of the immature oocytes retrieved in ICSI cycles were inferior to those of mature oocytes. Therefore, increasing the number of injectable oocytes and transferrable embryos by using immature oocytes after their spontaneous in vitro maturation does not necessarily improve pregnancy outcomes.

• Journal of Plant Biotechnology
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• v.6 no.4
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• pp.213-219
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• 2004

Zygotic embryos were excised from immature and mature seeds of the Himalayan yew, Taxus wallichiana. The embryos germinated precociously when kept in darkness for 5 weeks and developed into full seedlings within 10-12 weeks. The highest rate of embryo germination ($81\%$) was obtained in modified Lloyd & McCown' s woody plant medium containing macro and micronutrients at half strength supplemented with $1\%$ activated charcoal, which supported both the best embryonic growth ($43\%$) and seedling development ($32\%$). However, the supplementation of basal media with kinetin, thidiazuron, 6-benzyl aminopurine or $GA_3$ had no effect on the germination of the embryos. The embryos derived from immature seeds germinated but the frequency of embryonic growth was better in mature seeds. Stratification of seeds effected precocious germination of embryos. Seeds kept at $4^{\circ}C$ for 1 week germinated earlier and at a higher frequency irrespective of the stage of seed maturity, while the germination rate declined with prolonged cold treatment for 1 month at that same temperature. Analysis of taxanes in germinating seedlings revealed that root tissues contained high levels of taxol, 10-deacetyl-baccatin ill and baccatin ill as compared to shoots. Thus embryo culture technique appears to overcome the lengthy dormancy requirement of T. wallichiana seeds.