• Asian-Australasian Journal of Animal Sciences
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• v.13 no.2
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• pp.167-175
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• 2000

This paper describes the magnetic orientation of bull sperm separated into the head and the flagellum treated by DTT or heparin in a 5,400G static field. Semen samples collected from four bulls (Japanese Black) were mixed to the same sperm density. One percentage triton X-100 was used to extract the plasma membrane. The intact and demembranated sperm suspensions were treated with 20, 200, 2,000 mM DTT, 100, 1,000 or 10,000 units heparin solutions at $4^{\circ}C$ for 6 days. The decondensation of the sperm nuclei treated by DTT or heparin was examined by measuring the head area at 1, 3 and 6 days. After measuring the area, each sample was exposed to a 5,400G static magnetic field generated by Nd-Fe-B permanent magnets for 24 hours at room temperature. Results showed that the sperms were separated into the head and the flagellum through the DTT treatment. Almost of the separated heads showed that their long axis oriented perpendicularly to the magnetic lines of force, and most of the long axis perpendicularly oriented heads showed that their flat plane oriented perpendicularly in a 5,400G magnetic field. Also, the demembranation of the head tended to increase those perpendicular orientations, while those perpendicular orientations of the head declined with the decondensation of the sperm nuclei. These findings suggest that strong magnetic anisotropy for the perpendicular orientation of the long axis and the flat plane of the head occurs in the sperm nuclei in a 5,400G magnetic field. The separated flagellum showed lower parallel orientation, and the separated and demembranated flagellum showed parallel orientation to the magnetic lines of force in this magnetic field. These findings suggest that weak magnetic anisotropy of the parallel orientation of the flagellum occurs in the inside components in a 5,400G field.

• Korean Journal of Ichthyology
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• v.21 no.2
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• pp.81-86
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• 2009

The spermiogenesis and mature spermatozoa of Pseudobagrus fulvidraco were described by means of scanning and transmission electron microscopy. Spermiogenesis is characterized by lateral development of the flagellum, nuclear rotation, deep nuclear fossa formation and compaction into thick granules. The spermatozoa exhibit a round head containing a nucleus that lacks an acrosome, and having a midpiece and a flagellum. The midpiece is small and has a short cytoplasm including several mitochondria separated from the tail by the cytoplasmic canal. The flagellum contains the 9+2 classical axoneme structure and has two axonemal fins. The presence of axonemal fins in the flagellum is a common character in Bagridae. The interrelationships among the Bagridae as well as other teleosts are herein discussed.

• Ocean Science Journal
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• v.41 no.1
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• pp.53-57
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• 2006

A specimen of Aetobatus flagellum was collected at Uljin in June 2005 for the first time in Korea. This specimen is characterized by the cephalic fin, the long snout, the dorsal fin between pelvic fins, spiracles on the dorsal side of the disc, the deeply notched nasal curtain and the one row of the teeth in the lower and the upper jaws. And unlike Aetobatus narinari, it does not have any spots on the its dorsal side of the disc. We report this specimen as the first record from Korea and name it 'Bak-jui-ga-o-ri' in Korean.

• Korean Journal of Ichthyology
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• v.31 no.4
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• pp.208-213
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• 2019

Spermatozoa of Aphyocypris chinensis was studied by transmission electron microscopy. The investiation revaled that, spermatozoa display a round head, a small midpiece and a long tail region. In the spermatozoa, the nucleus contains highly condensed homogeneous chromation with small electron lucent areas. The base of the nucleus is slightly invaginated laterally by the nuclear fossa which contains the proximal centriole. The two centrioles orientated at an obtus angle (130°) to each other. The midpiece encircles the flagellum and is completely separated from it by the cytoplasmic channel. The midpiece contains more than 12 mitochondria. The mitochondria are arranged in 4~5 layer and are asymmetrically distributed in the postnuclear cytoplasm. The mitochondria surround the proximal part of the flagellum. The flagellum has classical 9+2 axoneme and no lateral fins. The spermatozoa of A. chinensis are similar to those of other cyprinids having a spherical head with a shallow nuclear fossa, a short midpiece including the asymmetrical arrangement of mitochondria and the lateral insertion of flagellum. However, there are some differences in the orientation of centrioles and the number of the mitochondria.

• Applied Microscopy
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• v.39 no.3
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• pp.245-252
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• 2009

The reproductive cells in testes of Microphysogobio yaluensis were investigated using light and electron microscopes. The testis of Microphysogobio yaluensis consisted of numerous testicular cysts contained synchronized cells. Sperms were full in testicular sacs of mature testes. Leydig cells were located among testicular cysts. The nucleus of primary spermatocytes was round and mitochondria were congregated in cytoplasm. The size of secondary spermatocyte was smaller than that of primary spermatocyte and the nucleus of a secondary spermatocyte was round or oval. In spermatids, the nucleus was round and electron-dense. In spermiogenesis, the nucleus was condensed and a flagellum started to be formed. The mitochondria were rearranged along the flagellum. The sperm had a round head, the acrosome was not found and a motile flagellum consisted of an axoneme with a typical 9+2 pattern of microtubule.

• The Korean Journal of Malacology
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• v.27 no.4
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• pp.377-386
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• 2011

The ultrastructures of germ cells during spermatogenesis and sperm morphology in male Mya arenaria oonogai, which was collected on the coastal waters of Samcheonpo, south coast of Korea, were investigated by transmission electron microscopic observations. In the early stage of the spermatid during spermiogenesis, a few granules and a proacrosomal granule, which is formed by the Golgi complex, appear on the spermatid nucleus, and then it becomes a proacrosomal vesicle. Consequently, it becomes an acrosome by way of the process of acrosome formation. The morphologies of the sperm nucleus type and the acrosome of this species have a curved cylindrical type and cone shape, respectively. The spermatozoon is approximately $48-50{\mu}m$ in length including a curved cylinderical sperm nucleus (about $2.65{\mu}m$ long), an acrosome (about $0.64{\mu}m$ in length) and tail flagellum ($40-45{\mu}m$ long). As some ultrastructural characteristics of the acrosomal vesicle, the peripheral parts of two basal rings show electron opaque part (region), while the apex part of the acrosome shows electron lucent part (region). These charateristics of the sperm belong to the family Myidae or some species of Veneridae in the subclass Heterodonta, unlike a characteristic of the subclass Pteriomorphia showing all part of the acrosome being composed of electron opaque part (region). Therefore, it is easy to distinguish the families or the subclasses by the acrosome structures. Exceptionally, In particular, a cylinder-like nucleus of the sperm is curved (the angle of the nucleus is about $20^{\circ}$), as seen in some species of Veneridae (range from $0^{\circ}-80^{\circ}$). The number of mitochondria in the midpiece of the sperm of this species are four, as one of common characteristics appeared in most species except for a few species in Veneridae in the subclass Heterodonta. Cross-sectioned axoneme of the sperm tail flagellum shows a 9+2 structure: the axoneme of the sperm tail flagellum consists of nine pairs of peripheral microtubules at the periphery and a pair of central doublets at the center.

• The Korean Journal of Malacology
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• v.27 no.2
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• pp.149-157
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• 2011

Some characteristics of the formations of acrosomal vesicles during the late stage of spermatids during spermiogenesis and taxonomical charateristics of sperm morphology in male two species (Saxidomus purpurata and Meretrix petechialis) in the family Veneridae were investigated by electron microscope observations. In two species, the morphologies of the spermatozoa have the primitive type and are similar to those of other bivalves in that it contains a short midpiece with five mitochondria surrounding the centrioles. The morphologies of the sperm nuclear types of S. purpurata and M. petechialis in Veneridae have the curved cylindrical and cylinderical type, respectively. And the acrosome shapes of two species are the same cap-shape type. In particular, the axial filament is not found in the lumen of the acrosome of two species, however, subacrosomal material are observed in the subacrosomal spaces between the anterior nuclear fossa and the acrosomal vesicle of two species. The spermatozoon of S. purpurata is approximately 46-$52{\mu}m$ in length, including a curved sperm nucleus (about $3.75{\mu}m$ in length), a long acrosome (about $0.40{\mu}m$ in length),and a tail flagellum (about 45-$47{\mu}m$ long). And the spermatozoon of M. petechialis is approximately 47-$50{\mu}m$ in length including a slightly curved sperm nucleus (about $1.50{\mu}m$ in length), an acrosome (about $0.56{\mu}m$ in length) and tail flagellum (44-$48{\mu}m$ in length). In two species, the axoneme of the sperm tail flagellum of each species consists of nine pairs of microtubules at the periphery and a pair of cental doublets at the center. Therefore, the axoneme of the sperm tail flagellum shows a 9 + 2 structure. In particular, taxonomically important some charateristics of sperm morphologies of two species in the family Veneridae are acrosomal morphology of the sperm, The axial filament is not found in the acrosome as seen in a few species of the family Veneridae in the subclass Heterodonta. The acrosomal vesicle is composed of right, left basal rings and the apex part of the acrosomal vesicle. In particular, right and left basal rings show electron opaque part (region), while the apex part of the acrosomal vesicle shows electron lucent part (region). These charateristics belong to the subclass Heterodonta, unlikely a characteristic of the subclass Pteriomorphia showing all part of the acrosome being composed of electron opaque part (region). Therefore, it is easy to distinguish the families or the subclasses by the acrosomal structures. The number of mitochondria in the midpiece of the sperm of S. purpurata and M. petechialis in Veneridae are five. However, the number of mitochondria in the midpiece of the sperm in most species of Veneridae in the subclass Heterodonta are four. Therefore, the number of mitochondria of the sperm midpiece of two species are exceptionally 5, and it is only exceptional case in the species in Veneridae in the subclass Heterodonta. Except these cases, the number of mitochondria in the sperm midpiece in all families in the subclass Heterodontaare are 4, and now widely used in taxonomic analyses.

• International Journal of Fluid Machinery and Systems
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• v.4 no.3
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• pp.341-348
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• 2011

The study of bacterial flagellar swimming motion remains an interesting and challenging research subject in the fields of hydrodynamics and bio-locomotion. This swimming motion is characterized by very low Reynolds numbers, which is unique and time reversible. In particular, the effect of rotation of helical flagella of bacterium on swimming motion requires detailed multi-disciplinary analysis. Clear understanding of such swimming motion will not only be beneficial for biologists but also to engineers interested in developing nanorobots mimicking bacterial swimming. In this paper, computational fluid dynamics (CFD) simulation of a three dimensional single flagellated bacteria has been developed and the fluid flow around the flagellum is investigated. CFD-based modeling studies were conducted to find the variables that affect the forward thrust experienced by the swimming bacterium. It is found that the propulsive force increases with increase in rotational velocity of flagellum and viscosity of surrounding fluid. It is also deduced from the study that the forward force depends on the geometry of helical flagella (directly proportional to square of the helical radius and inversely proportional to pitch).

• Applied Microscopy
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• v.26 no.3
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• pp.267-275
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• 1996

The internal ultrastructural changes of germ cells and external morphology of spermatozoon during the spermatogenesis in the rockfish, Sebastes inermis were studied using transmission and scanning electron microscope. The testis is seminiferous tubule type in internal structure. Seminiferous tubule consist of many cyst which contain numerous germ cells in same developmental stage. Spermatogonium contained a large nucleus with single nucleolus in interphase. Primary spermatocyte identified by the presence of synaptonemal complex in nucleus and the contained a number of mitochondria, endoplasmic reticula and Golgi bodies in cytoplasm. The nucleoplasm of secondary spermatocyte was more concentrated than that of the previous phase. Spermatids were more condensed in nucleus and cytoplasm, and show the long-spherical shape. In the cytoplasm of spermatid mitochondria located to lower portion of the nucleus and Golgi bodies located to upper portion, but proacrosomal granule is not appeared. The spermatozoon consist of the head and tail. No acrosome could be found in the head. The cytoplasmic collar of posterior part in sperm head contained mitochondria which surrounded axial filament. The well developed axonemal lateral fins were identified in sperm flagellum, and the axial filament of the flagellum consist of nine pairs of peripheral microtubules and one pair of central microtubules.

• The Korean Journal of Malacology
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• v.24 no.1
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• pp.1-10
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• 2008

Spermatogenesis and the reproductive cycle in male Spisula sachalinensis were investigated by cytological and histological observations. The morphology of the spermatozoon has a primitive type and is similar to those of other bivalves in that it contains a short midpiece with four mitochondria surrounding the centrioles. But spermatozoon of this species has not axial rod and satellite body in the midpiece. The morphologies of the sperm nucleus type and the acrosome shape of this species have a globe-shape type and modified cap-like shape, respectively. The spermatozoon is approximately $40-45{\mu}m$ in length including the sperm nucleus length (about $1.35{\mu}m$), acrosome length (about $1.50{\mu}m$) and tail flagellum. The axoneme of the sperm tail flagellum consists of nine pairs of microtubules at the periphery and a pair at the center. The axoneme of the sperm tail shows a 9+2 structure. The spawning period of these species lasts from June to July, and the main spawning occurs in July when seawater temperatures are greater than $20^{\circ}C$. The male reproductive cycle of this species can be categorized into five successive stages: early active stage (October to January), late active stage (February to April), ripe stage (April to June), partially spawned stage (June and July), and spent/inactive stage (August to September).