• Journal of Korean Neurosurgical Society
• /
• 제64권3호
• /
• 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
• /
• 제6권2호
• /
• 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
• /
• 제51권1호
• /
• 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
• /
• 제14권1호
• /
• 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
• /
• 제36권4호
• /
• 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
• /
• 제4권4호
• /
• 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.

• 한국동물학회지
• /
• 제30권3호
• /
• 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.

• 식물조직배양학회지
• /
• 제21권3호
• /
• pp.157-160
• /
• 1994

국내 두 품종의 고구마를 대상으로 경단분열조직 배양에 의한 체세포배발생과 이들로부터 식물체 재분화 체계를 확립하였다. '부여재래' 나 '율미'의 경단분열조직 절편을 1mg/L 2,4-D가 첨가된 MS배지에서 배양하여 6주후에 80% 이상의 절편으로부터 배발생 캘러스를 얻었다. 이 캘러스를 0.1 mg/L 24-D와 0.1 mg/L kinetin이 첨가된 배지에 옮겼을때 '부여재래' 와 '율미'의 체세포배 발생률이 각각 71% 및 63％로 다른 처리에 비해 현저히 높았다. 형성된 체세포배를 상하로 이등분하여 1 mg/L 2,4-D가 첨가된 MS배지에 치상하였을 경우 품종에 관계없이 길이가 짧은 체세포배의 상반부에서 이차배가 더 많이 발생하였다. 이들 체세포배는 MS 기본배지에서 90％ 이상이 완전한 식물체로 발달하였다. 이러한 결과는 우리가 이전에 확립하였던 고구마의 경단분열조직으로부터의 체세포배발생 방법(SABRAO J 21:93-101)이 광범위한 고구마 계통에 적용될 수 있음을 시사한다.

• 한국초지조사료학회지
• /
• 제19권4호
• /
• pp.297-302
• /
• 1999

알파파의 재분화된 식물체로부터 다량의 이차체세포배를 유도하였으며, 이들 체세포배로부터 재분화되는 식물체의 획득빈도를 향상시키기 위하여, 캘러스에서 유래된 배의 형태 및 형태별 유식물 분화 양상에 관한 실험을 수행하였다. 2,4-D 농도에 따라 체세포배의 형성에 차이를 나타내었는데, 생장조절제가 첨가되지 않았거나, 2,4-D가 $0.1mg/{\ell}$ 첨가된 배지에서 형성된 배는 약 57% 이상이 2개의 자엽을 갖은 정상배였으며, 2,4-D 농도가 증가할수록 정상체세포배의 출현빈도는 감소하였고, 2,4-D $4mg/{\ell}$에서는 10%만이 정상배로 나타났다. 배의 형태에 따른 발아율 및 유식물 분화양상을 조사한 결과, 2개의 자엽을 갖는 정상배의 경우는 발아율이 85%로 가장 높았으며, 정상식물체로 발육되는 비율도 80%로 나타났다. 그러나 자엽이 1개 또는 3~4개인 배는 정상적으로 발육되는 식물체의 비율이 10% 이하로 매우 낮았으며, 자엽이 5개인 배와 나팔모양의 배는 정상적인 식물체로 발달하지 못하였다.

• 식물조직배양학회지
• /
• 제28권1호
• /
• pp.21-24
• /
• 2001

식용 및 약용으로 사용되는 갯기름나물의 기내배양을 통한 재분화율을 조사하였다. 캘러스는 잎과 엽병의 절편체에서 발생하였고 0∼5 mg/L의 NAA와 0∼10 mg/L BA가 첨가된 MS 기본배지에 치상하여 암배양 결과 자발적인 배 분화와 기관 분화를 보여주었으며 2.5 mg/L NAA와 10 mg/L BA의 조건에서 재분화율이 가장 높았다. 체세포 배의 발생양상은 구형, 심장형, 어뢰형을 거쳐 자엽 단계로 발달하여 전형적인 접합자 배의 모습으로 발달하였다. 배 발생한 일차 체세포배를 0.2 mg/L의 NAA가 첨가된 배지에서 배양하였을 때, 이차 체세포배가 발생하였으며 주로 일차 체세포배의 배축과 하배축에서 많이 발생하였고 그 다음으로 자엽이나 뿌리 부분에서 발생하였다.