• Applied Microscopy
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• 제21권2호
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• pp.1-13
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• 1991

In order to investigate the factors of the control mechanism of somitogenesis, early chick embryos (H-H stage $8{\sim}13$) were treated with heat shock, ${\alpha}$-amanitin and cycloheximide and morphological changes of somite were examined by light microscopy, transmission and scanning electron microscopy. In normal chick embryo, somites were formed from the somitomere which preexisted in segmental plate. Somites were wrapped with extracellular collagen fibrils and connected with neural tube, notochord and ectoderm. And then, somites were differentiated to sclerotome, dermatome and myotome by the interaction of nervous tissue. Abnormal somites were observed after formation of six or seven so mites in heat shock treated group. Amounts of collagen fibrils were obviously decreased in this group. In cycloheximide treated group, most so mites were smaller and neural tube formation was incomplete. Chromatins were condenced and formed several heterochromatins in the nucleus of somite cells. Lipid like cytoplasmic dense mass and lipid droplets were also observed. Segmentation of somites seemed to be normal progress in ${\alpha}$-amanitin treated group. Center of somite, however, hollowed in longitudinal sectioned samples. These results suggested that so mites were already existed in the segmental plate as the form of somitomere. Segmented somites were contacted with neural tube or notochord and the somites were tightly connected with each other by the extracellular collagen fibrils which were secreted from neuroepithelium and somite cells. Somites are thought to differentiate into sclerotome, dermatome and myotome by these interactions.

• Animal cells and systems
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• 제10권1호
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• pp.7-14
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• 2006

Novactaea pulchella was reared in the laboratory, from hatching to the megalopal stage at $25^{\circ}C$. The larval stage of it consists of two zoeal and one megalopal stages. The first zoea of the present study differs from that described by Terada (1990) in the setal presence of the carapace, the maxilla and the maxilliped, and the lateral process on the abdominal somite. It is reported for the first time that brachyuran zoeas belonging to a species share two types of lateral processes on the abdominal somites. They are either on the abdominal somites 2 and 3 or on abdominal somites 2 to 5. A provisional key is provided to aid the identification of the actaeine zoeas in Korea and the adjacent waters.

• Animal cells and systems
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• 제11권1호
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• pp.79-92
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• 2007

Eight zoeal stages and one decapodid of the hippolytid shrimp Latreutes acicularis Ortmann, 1890 are described from laboratory-reared material hatched from egg from ovigerous females collected from Shimoda, Japan. The presence of a minute dorsomedian protuberance on the third abdominal somite, the spinules on the dorsal margin of the fourth and fifth abdominal somites, and a pair of dorsolateral spines on the fourth and fifth abdominal somites readily distinguish the larvae of L. acicularis from those of L. anoplonyx Kemp, 1914 and L. laminirostris Ortmann, 1890, the other two known larvae of Latreutes from East Asia.

• Toxicological Research
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• 제20권2호
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• pp.117-122
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• 2004

The present study was carried out to establish a short-term teratogenicity study for detecting developmental toxic potential induced by gamma radiation in ICR mice. Pregnant mice were exposed at dose levels of 0, 0.5, 1, 2, or 4 Gy on gestational day 8.5. All dams were subjected to caesarean section on gestational day 10.5 and their embryos were examined for growth, differentiation, and morphological abnormalities. An increase in the number of resorption was found at 4 Gy in a dose-dependent manner. Dose-dependent decreases in the developmental score of yolk sac circulation and olfactory system at above 1 Gy, in the number of somite pairs and developmental score of allantois, optic system, and maxillary process at above 2 Gy, and in the all growth and developmental parameters examined at 4 Gy were found. Various types of morphological abnormalities were seen at dose levels of 0.5 Gy or greater. Characteristic malformations induced by gamma radiation were abnormal axial rotation, hematoma, craniofacial hypoplasia, open neuropore, shortened prosencephalon, kinked somites, irregular somites, swelling, hydropericardium, absent branchial bar, and absent limb bud. Morphological alterations such as hematoma, craniofacial hypoplasia, open neuropore, and kinked somites were noted even in the lowest dose (0.5 Gy). These results indicated that the short-term teratogenicity study established in this study can be a useful tool for not only detecting the developmental toxic potential induced by gamma radiation, but also screening radio-protective agents in ICR mice.

• Animal Systematics, Evolution and Diversity
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• 제36권4호
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• pp.304-308
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• 2020

Ovigerous crab of Echinoecus nipponicus of subfamily Eumedoninae in Pilumnidae was collected from Seogwipo, Jejudo and hatched in the laboratory. The first zoeal stage of E. nipponicus is reported for the first time in the world and its digital image of live zoeas is provided. The first zoea of E. nipponicus has yellowish red chromatophores which occurring behind eyes, on dorsal spine and on anterior margin of telson, reddish brown chromatophores on abdominal somites 2-5 ventrally, dorsal, rostral, and lateral spines shorter than carapace length, three aesthetascs and two setae on the antennule, two medial setae on the antennal exopod, lateral processes on the abdominal somites 2, 3, and two lateral spine and one dorsomedial spine on the telson.

• Animal Systematics, Evolution and Diversity
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• 제34권3호
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• pp.127-142
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• 2018

A new species of Eudactylopus Scott A., 1909 is described from the southern coast of Korea. The specimens were collected using a light trap set overnight at the entrance near a pier. Eudactylopus yokjidoensis n. sp. is similar to E. andrewi Sewell, 1940 and E. spectabilis (Brian, 1923) in two key respects: similar length of proximal and distal inner setae on female P2 enp-2, and modification of two subapical setae on male P2 endopod. However, E. yokjidoensis can be differentiated from the two species by following morphological characteristics: in females, the length ratio of cephalothorax/2nd-4th thoracic somites combined is smaller in E. yokjidoensis than other two species (1 : 0.8 vs. 1 : 1); antennule has nine segments (vs. 7-segmented in E. andrewi); P2 to P4 each bears a process in medial distal margin of basis, while it is just smooth in E. spectabilis; in males; the length ratio of cephalothorax to 2nd-4th thoracic somites combined is smaller in E. yokjidoensis than other two species (1 : 0.6 vs. 1 : 1 in E. andrewi and 1 : 0.8 in E. spectabilis); and P5 exopod has a comb-like innermost seta, while it is bipinnate seta in E. spectabilis. To prove the Korean species of Eudactylopus to be new, full descriptions of both sexes are given here, and the claim is supported by distinct genetic differences between E. yokjidoensis and E. spectabilis (22.3-22.7%) in the mitochondrial gene cytochrome oxidase subunit I(mtCOI) sequence.

• Animal cells and systems
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• 제13권1호
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• pp.59-69
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• 2009

This paper documents the defining morphological characteristics of the larval stages of Chionoecetes tanneri Rathbun, 1893, the grooved Tanner crab, from specimens reared in the laboratory. Chionoecetes tanneri larval stages include two zoeae and one megalopa. The first zoea is characterized by: six setae on the posterior margin of the carapace; postero-lateral spines on abdominal somites 3 and 4, extending beyond the posterior margin of adjacent somites and bearing 9-10 spinnules; 12 plumose setae and one stout distal plumose seta present on the margin of the scaphognathite of the maxilla; and one fused lateral spine and one articulated dorso-medial spine on each fork of the telson. The second zoea is characterized by: 9 setae on the postero-lateral margin of the carapace; a serrated mandible molar; a mandibular palp bud; 25-26 plumose setae on the margin of the scaphognathite of the maxilla; pereiopods with well-developed gills and buds; and four pairs of stout setae on the posterior margin of the telson. For the megalopal stage, the distinguishing characteristics include: a rostral spine equal in length to the supraorbital spine; six setae on the exopod of the uropod; and a single spine on the ischium of the second pereiopod. This study allows C. tanneri larvae to be distinguished from the larvae of known sympatric congeners. This information provides a basic taxonomic tool for researchers in fisheries management and zooplankton ecology who are addressing issues related to trophic interactions, metapopulation dynamics and ecosystem impacts in the evolving marine resource management strategies in the North Pacific, and those related to Chionoecetes species in particular.

• Journal of Species Research
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• 제1권1호
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• pp.4-34
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• 2012

Parastenocaris koreana sp. nov. is described based on examination of numerous adult specimens of both sexes from several localities in Korea. Scanning electron micrographs are used to examine intra- and interpopulation variability of micro-characters, in addition to light microscopy. The new species is most closely related to the Japanese P. biwae Miura, 1969, which we redescribe based on newly collected material from the Lake Biwa drainage area. The two species differ in size, relative length of the caudal rami, shape of the anal operculum, shape of the genital double somite, relative length of the inner distal process on the female fifth leg, as well as relative length of the apical setae on the second, third, and fourth legs exopods in both sexes. Detailed examinations of three disjunct populations of P. koreana reveal also some geographical variation, especially in the surface ornamentation of somites, which may indicate some population structuring or even cryptic speciation. Lack of intraspecific variability in the number and position of sensilla on somites, as well as their potential phylogenetic significance, is a novel discovery. Both species examined here belong to the brevipes group, which we redefine to include 20 species from India (including Sri Lanka), Australia, East Asia, Northern Europe, and North America. A key to species of this group is also provided. In order to test the monophyly of the redefined brevipes group with highly disjunct distribution, as well as relationship between different species, a cladistics analysis is performed based on 39 morphological characters and with help of three outgroup taxa. Six equally parsimonious cladograms are generated, all of which show that the ingroup is well defined by at least three synapomorphies. Reconstructed phylogeny questions the previously suggested hypothesis about the origin of this group in South East Asia, with one Australian species showing the most basal position. We speculate that the present distribution of this group may be a combination of ancient vicariance and subsequent dispersal, with a possible origin in the Gondwanaland, in the rift valley between Australia and India.

• 한국동물번식학회:학술대회논문집
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• 한국동물번식학회 2004년도 춘계학술발표대회
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• pp.275-275
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• 2004

To evaluate the potential of the stem cell therapy as a method for prenatal management of spinal open neural tube defect (ONTD), the influence of embryonic stem cells injected into the amniotic cavity on the re-closure capacity of spinal ONTD was investgated. Spinal neural tube was incised open for a length of 6 somites using chick embryos of Hamburger and Hamilton stage 18 or 19. (omitted)

• Animal Systematics, Evolution and Diversity
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• 제30권2호
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• pp.144-150
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• 2014

Two species of hippolytid shrimps, Eualus kuratai Miyake and Hayashi, 1967 and Heptacarpus igarashii Hayashi and Chiba, 1989, were collected at a sea cucumber farm from the East Sea. These species are described and illustrated for the first time in Korea. Eualus kuratai is closely related to E. middendorffi; however, it lacks a dorsomedian spine on the fourth and fifth abdominal somites. Heptacarpus igarashii can be easily distinguished from other Korean Heptacarpus species due to its short rostrum that lacks ventral teeth on margin. This report extends the previously known ranges from Japan and Korea. In Korea, both genera, Eualus and Heptacarpus, have seven species according to the present report, respectively; moreover, hippolytid shrimps now consist of 31 species of nine genera.