• Journal of Korean Neurosurgical Society
• /
• v.64 no.3
• /
• pp.346-358
• /
• 2021

Secondary neurulation is a morphological process described since the second half of the 19th century; it accounts for the formation of the caudal spinal cord in mammals including humans. A similar process takes place in birds. This form of neurulation is caused by the growth of the tail bud region, the most caudal axial region of the embryo. Experimental work in different animal species leads to questioning dogmas widely disseminated in the medical literature. Thus, it is clearly established that the tail bud is not a mass of undifferentiated pluripotent cells but is made up of a juxtaposition of territories whose fate is different. The lumens of the two tubes generated by the two modes of neurulation are continuous. There seem to be multiple cavities in the human embryo, but discrepancies exist according to the authors. Finally, the tissues that generate the secondary neural tube are initially located in the most superficial layer of the embryo. These cells must undergo internalization to generate the secondary neurectoderm. A defect in internalization could lead to an open neural tube defect that contradicts the dogma that a secondary neurulation defect is closed by definition.

• Journal of Plant Biology
• /
• v.6 no.2
• /
• pp.3-6
• /
• 1963

As a part of embryological studies of Panax ginseng, megasporangium and megagametophyte formations were investigated. Ovule is found to be auatropous. Small-sized nucellus is surrounded by thick layered single integument. As the embryo sac develops, the nucellus along with some parts of the inner epidermis of integument disintegrates and completely disappers at flowering stage. Embryo sac takes the type of typical Polygonum although antipodal cells disappear and polar nuclei fuse to form secondary nucleus before fertilization. Mature embryo sac consists of egg apparatus and large secondary nucleus lying adjacent to the egg. Besides the normal ovule, tiny incomplete ovule develops near the base of style. Frequently two normal ovules are formed in a single locule. Chromosome number counted is PMC is n=24.

• Clinical and Experimental Reproductive Medicine
• /
• v.51 no.1
• /
• pp.63-68
• /
• 2024

Objective: This study was conducted to investigate the impact of previous delivery mode on pregnancy outcomes in patients with secondary infertility after frozen-thawed embryo transfer. Methods: This prospective observational study included 140 patients experiencing secondary infertility. Of these, 70 patients had a previous cesarean delivery (CD), while the remaining 70 patients had a previous normal vaginal delivery (NVD). The primary outcome was the implantation rate. The secondary outcomes included rates of clinical pregnancy, chemical pregnancy, miscarriage, and ectopic pregnancy. Results: The comparison of all fertility outcomes between the two groups revealed no statistically significant differences. The implantation rate was 40.4% in the CD group and 41.7% in the NVD group (p=0.842). The clinical pregnancy rate was 50% in the CD group and 49.3% in the NVD group (p=0.932), while the chemical pregnancy rate was 14.6% in the CD group and 19% in the NVD group (p=0.591). The miscarriage rates in the CD and NVD groups were 20% and 17.6%, respectively (p=0.803). One case of tubal ectopic pregnancy occurred in the NVD group (1.4%). Conclusion: The mode of prior delivery did not significantly impact pregnancy outcomes following frozen-thawed embryo transfer.

• Food Science and Biotechnology
• /
• v.14 no.1
• /
• pp.102-107
• /
• 2005

In this study, the ameliorating effect of soybean embryos on the impact of alcohol consumption was investigated on rat hepatocytes and in reducing total serum cholesterol levels and total serum lipid levels. Liver histology and two clinically important enzyme markers, aspartate aminotransferase (AST) and alanine aminotransferase (ALT), of rats administered with both alcohol and soybean embryo were compared with a control group. The treatment regimen of soybean embryo significantly reduced the serum ALT and AST levels of the subjects, demonstrating the hepato-protective effects of soybean embryo. Electron microscopy indicated that the administration of soybean embryo preserved the important hepatocyte structures and prevented the presence of lipid droplets and secondary lysosomes. Furthermore, total cholesterol and total lipid levels were significantly reduced. These results indicate that treatment with soybean embryo can positively mediate the effects of alcohol on hepatocytes and general liver functions.

• Journal of Ginseng Research
• /
• v.36 no.4
• /
• pp.442-448
• /
• 2012

Somatic embryogenesis is one of good examples of the basic research for plant embryo development as well as an important technique for plant biotechnology such as medicinally important plants. Single embryos develop into normal plantlets with shoots and roots. Therefore, direct single embryogenesis derived from single cells is highly important for normal plant regeneration. Here we demonstrate that the cyclic secondary somatic embryogenesis in Panax ginseng Meyer is a permanent source of embryogenic material that can be used for genetic manipulations. Secondary somatic embryos were originated directly from the primary somatic embryos on hormone-free Murashige and Skoog medium, and proliferated further in a cyclic manner. EM medium (one third of modified MS medium [MS medium containing half amount of NH4NO3 and KNO3] with 2% to 3% sucrose) favored further development of proliferated secondary somatic embryos into plantlets with root system. The plantlets developed into plants with well-developed taproots in half-strength Schenk and Hildebrandt basal medium supplemented with 0.5% activated charcoal.

• Plant Biotechnology Reports
• /
• v.4 no.4
• /
• pp.261-267
• /
• 2010

We describe culture conditions for a high-efficiency in vitro regeneration system of Papaver nudicaule through somatic embryogenesis and secondary somatic embryogenesis. The embryogenic callus induction rate was highest when petiole explants were cultured on Murashige and Skoog (MS) medium containing 1.0 mg $1^{-1}$ ${\alpha}$-naphthaleneacetic acid (NAA) and 0.1 mg $1^{-1}$ 6-benzyladenine (BA) (36.7%). When transferred to plant growth regulator (PGR)-free medium, 430 somatic embryos formed asynchronously from 90 mg of embryogenic callus in each 100-ml flask. Early-stage somatic embryos were transferred to MS medium containing 1.0 mg $1^{-1}$ BA and 1.0 mg $1^{-1}$ NAA to germinate at high frequency (97.6%). One-third-strength MS medium with 1.0% sucrose and 1.0 mg $1^{-1}$ $GA_3$ had the highest frequency of plantlet conversion from somatic embryos (91.2%). Over 90% of regenerated plantlets were successfully acclimated in the greenhouse. Secondary somatic embryos were frequently induced directly when the excised hypocotyls of the primary somatic embryos were cultured on MS medium without PGRs. Sucrose concentration significantly affected the induction of secondary embryos. The highest induction rate (89.5) and number of secondary somatic embryos per explant (9.3) were obtained by 1% sucrose. Most secondary embryos (87.2-94.3%) developed into the cotyledonary stage on induction medium. All cotyledonary secondary embryos were converted into plantlets both in liquid and on semisolid 1/3-strength MS medium with 1.0% sucrose.

• The Korean Journal of Zoology
• /
• v.30 no.3
• /
• pp.248-260
• /
• 1987

In order to investigate the importance of the prospective mesodermal and endodermal blastomeres at 32-cell stage in the anis formation, blastomeres were deleted or transplanted into the ventrovegital site of another normal embryo. The results are as follows: When the dorsomesodermal or dorsoendodermal blastomeres were deleted, there was a substantial developmental lesion in the axis structure. However, when the ventromesodermal or ventroendodermal blastomeres were deleted, the formation of an axis structure was nearly normal. The dorsomesodermal or dorsoendodermal blastomeres which were transplanted into the ventral side of the normal 32-cell embryo caused the formation of a secondary body axis, and the capacity of the second axis induction in the dorsomesodermal blastomeres was a little higher than that in the dorsoendodermal blastomeres. These results imply that both the dorsomesodermal and dorsoendodermal blastomeres are involved in the formation of a set of dorsal body structures during early embryogenesis. As well, in order to investigate the axis inducing capacity in the early cleavage embryos, the dorsovegital blastomeres were transplanted into the ventrovegital site at 4-cell, 8-cell and 16-ceIL stage respectively. As a ruts·fIt, a second body axis was formed. Therefore, it seems that the early cleavage embryo as 4-cell stage dorsal blastomeres contain some informations necessary for the axis formation.

• Korean Journal of Plant Tissue Culture
• /
• v.21 no.3
• /
• pp.157-160
• /
• 1994

Culture conditions for high Sequency somatic embryogenesis and plant regeneration in tissue cultures of sweet potato of two Korean cultivars 'Puyojaerae' and 'Yulmi' are described. Shoot apical meristem explants (height 150 $\mu\textrm{m}$; base: 350 $\mu\textrm{m}$) were cultured on MS medium supplemented with 1 mg/L 2,4-D. After 6 weeks of culture, greater than 80% of the survived explants produced embryogenic calli. When transferred onto MS medium with 0.1 mg/L each of 2,4-D and kinetin, the calli gave rise to somatic embryos at frequencies of 71% ('Puyojaerae') and 63% ('Yulmi'), respectively: When somatic embryos at various developmental stages measured in length were transversely cut into two halves and cultured on MS medium with 1 mg/L 2,L-D, the upper halves produced secondary embryos more frequently than the lower ones, and halves of somatic embryos less than 1 mm in length had a higher competence for secondary embryo formation than longer ones of either cultivar. However 'Puyojaerae' somatic embryo halves showed a higher frequency of secondary embryo formation than 'Yulmi' ones on the whole. Upon transfer onto MS basal medium, most of the primary and secondary somatic embryos underwent development into plantlets. The plantlets were transplanted to potting soil and grown to maturity in a phytotron. The overall results suggest that the shoot apical meristem culture system for somatic embryo formation in sweet potato previously established by us (SABRAOJ 21: 93-101) may be applicable regardless of it genotypes.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.19 no.4
• /
• pp.297-302
• /
• 1999

Cotyledonary abnormalities were observed in secondary somatic embryos which were developed from calli cultured on MS medium with various concentrations of 2,4-D. In MS medium containing hormone-free or $0.1mg/{\ell}$ 2,4-D, the frequency of normal embryo formation with two cotyledons were above 57%. According to concentration of 2,4-D increment the frequency of normal embryos were decreased. In MS medium containing $4mg/{\ell}$ 2,4-D, the frequency of normal embryo formation was just 10%. The rate of germination was as follows; 37.7% of somatic embryos had one cotyledon, 85% two cotyledons, 38% three cotyledons, 35% four cotyledons, 25% five cotyledons and 29% trumpet-like cotyledons. About 80% of the embryos with two cotyledons were converted into normal plants, but one, three or four cotyledons were only 6.8~10%. The five or trumpet-like embryos were not developed into normal plants.

• Korean Journal of Plant Tissue Culture
• /
• v.28 no.1
• /
• pp.21-24
• /
• 2001

Peucedanum japonicum $T_{HUNB}$ used as a edible and medicinal plants was investigated for in uitro regeneration. Callus formation occurred on leaf and stem explant cultures and showed spontaneous embryogenic and organogenic capability on MS basal medium supplemented with 0.1~5 mg/L NAA and 0~10 mg/L BA in dark. The regeneration was highest on the condition supplemented with 2.5 mg/L NAA and 10 mg/L BA. Development of the somatic embryo progressed through the globular, heart-shaped, torpedo-shaped and cotyledonary stage, typical of zygotic embryos. When the first somatic embryos was cultured on the medium supplemented with 0.2 mg/L NAA, secondary somatic embryo were induced with higher frequency on the hypocotyl then on the cotyledon and root.t.