• Development and Reproduction
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• v.2 no.1
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• pp.101-109
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• 1998

Spermatogenesis and reproductive cycle of the razor clam, solen grandis, were investigated monthly by histological and cytological observations. Samples were collected from natural intertidal population at Oshik-do, Kunsan, Korea, for one year, beginning from January to December, 1993. solen grandis is dioecious. Morphological structures of the spermatozoon of this species ar esimilar to those of other bivalve spermatozoa having a primitive type; i.e., a small head, a cap-shaped acrosome and a short mid-piece with four mitochondria surrounding axial filament. The head of spermatozoon is approximately 2 \mu m in length and sperm tail is about 20 \mu m long. The axoneme of tail flagellum consists of nine pairs of peripheral microtubules at the periphery and a pair of central microtubules at the center. Four spherical mitochondria form the paranucleus. Spawning occures once a year between early June and July, and the main spawning was observed in July when seawater temperature reaches above 20 \circ C. The reproductive cycle of male razor clam can be divieded into fivesuccessive stages; early active (December to january), late active (January to march), mature (March to early August), partially spawned (June to July), and spent/inactive stage (August to December).

• Parasites, Hosts and Diseases
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• v.47 no.3
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• pp.287-291
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• 2009

The ${\alpha}/{\beta}$-tubulin heterodimer is the basic subunit of microtubules in eukaryotes. Polyclonal antibodies specific to recombinant ${\alpha}$-tubulin of Giardia lamblia were made, and found effective as a probe to specifically detect G. lamblia by immunofluorescence assays. Nucleotide sequences of ${\alpha}$-tubulin genes were compared between G. lamblia WB and GS strains, prototypes of assemblage A and assemblage B, respectively. A set of primers was designed and used to amplify a portion of the ${\alpha}$-tubulin gene from G. lamblia. PCR-RFLP analysis of this ${\alpha}$-tubulin PCR product successfully differentiated G. lamblia into 2 distinct groups, assemblages A and B.Theresults indicate that ${\alpha}$-tubulin can be used as a molecular probe to detect G.lamblia.

• Applied Microscopy
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• v.26 no.2
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• pp.221-233
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• 1996

In order to study process of spermiogenesis of the Korean manchurian field mouse, Apodemus spesiosus peninsulae, the testis obtained from sexually matured male reproductive organs, were examined with electron microscopy, and the following results were obtained based on the characters of cell differentiation. 1. According to the features of cell structure, spermiogenesis of the Apodemus spesiosus peninsulae was five phases: Golgi, cap, acrosome, maturation and spermiation phase. They were further subdivided into two steps of early and late phases respectively. Hence, the spermiogenesis consists of ten steps. 2. In the changes of the chromatin, the chromatin granules began to be condenced in the cap phase and regularizated at maturation phases, and a perfect nucleus of sperm was formed at the spermiation phases. 3. The formative period of sperm tail began to be develop in the early Golgi phase and completed at the spermiation phases 4. The outer dence fibers of middle piece were arranged in a horseshoe fashion. Nos. 1, 5, 6 and 9 of the outer dense fibers were larger than the others. The structure of axoneme in the middle piece was 9+2, and the axonemal complex consists of A and B microtubules, dynein arms and radial links.

• Development and Reproduction
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• v.20 no.1
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• pp.11-22
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• 2016

The ultrastructures of germ cells and the functions of Leydig cells and Sertoli cells during spermatogenesis in male Kareius bicoloratus (Pleuronectidae) were investigated by electron microscope observation. Each of the well-developed Leydig cells during active maturation division and before spermiation contained an ovoid vesicular nucleus, a number of smooth endoplasmic reticula, well-developed tubular or vesicular mitochondrial cristae, and several lipid droplets in the cytoplasm. It is assumed that Leydig cells are typical steroidogenic cells showing cytological characteristics associated with male steroidogenesis. No cyclic structural changes in the Leydig cells were observed through the year. However, although no clear evidence of steroidogenesis or of any transfer of nutrients from the Sertoli cells to spermatogenic cells was observed, cyclic structural changes in the Sertoli cells were observed over the year. During the period of undischarged germ cell degeneration after spermiation, the Sertoli cells evidenced a lysosomal system associated with phagocytic function in the seminiferous lobules. In this study, the Sertoli cells function in phagocytosis and the resorption of products originating from degenerating spermatids and spermatozoa after spermiation. The spermatozoon lacks an acrosome, as have been shown in all teleost fish spermatozoa. The flagellum or sperm tail of this species evidences the typical 9+2 array of microtubules.

• Korean Journal of Animal Reproduction
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• v.19 no.3
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• pp.205-216
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• 1995

Microtubules와 micrfilaments는 포유동물 난자이 주요한 세포 구조물들로, 이들은 난자의 성숙, 수정 및 배발달시 핵질의 이동과 세포질 분열에 직접 관여하는 것으로 알려져 왔다. 난자내 세포구조물의 정확한 움직임은 정상적인 배 발달을 위해 필수적이다. Microtubules는 $\alpha$, $\beta$- bubulin이 서로 연결되어 이루어져 있으며, 수정시 웅성.자성전핵 움직임과 세포분열시, 유사 및 감수분열시 그 역할을 한다. 생쥐를 제외한 대부분의 동물에서 microbubules의 역할은 수정시 정자가 centrosome을 난자내로 이전하여 sperm aster를 형성함으로써 시작된다고 보고되고 있다. 따라서 정자의 도움없이 배발달이 일어나는 단위발생시 microbubules의 형성은 연구들 사이에 흥미로운 연구대상이 되고 있다. 한편 microfilaments는 세포분열시 세포질을 분할하는 기계적인 역할을 하는 것으로 알려져 있으며, 최근 생쥐 난자에서는 정자의 난자내 융합과 웅성 및 자성 전핵의 이동에 관여한다고 보고되고 있다. 포유동물 난자의 체외성숙, 체외수정을 유도할 때 여러 가지 비정상적인 핵움직임과 세포분열이 관찰되어지고, 낮은 배발달율이 보고되고 있는데, 최근 연구자들은 세포구조물, 즉 microtubules와 microfilaments의 비정상적인 역할에서 기인한다고 보고 있다. 따라서 포유동물 난자의 성숙.수정 및 단위발생시 세포구조물의 움직임과 역할 및 상호관계에 대한 정확한 이해는 체외수정율 및 배발달 향상에 중요한 기초자료로 이용되리라고 본다.

• Development and Reproduction
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• v.1 no.1
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• pp.9-24
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• 1997

To investigate the process of spermiogenesis of the Korean eastern Daubenton's bat, Myotis daubentonii ussuriensis, the testis obtained from mature male bats was studied by transmission electron microscope and were based on the variety and diagnostic characters of cell organells. The results obtained from the present study are as follows. According to the differentiation of the cell organells, the spermiogenesis of the Korean eastern Daubenton's bat, M. d. ussuriensis, was divided into Golg, cap, acrosome, maturation and spermiation phases. Besides, these Golgi, cap, acrosome, and maturation phase were subdivided into the steps of early and late phases repectively and matruation phase was subdivided into step of early, mid and late phases. Therfore, the spermiogenesisof M. d. ussuriensis has been divided into a total of 11 phases. The chromatin granules began to condense at the early cap phase, regularized at the acrosome phase, and a perfect nucleus of sperm was formed at the maturation phase. The chromatoid body was occurred in the upper cytoplasm of nucleus at the early Golgi phase, and it was accurred the posterior cytoplasm of the nucleus at the early maturatio phase. The formation of sperm tail began to be develop in the early golgi phase, and completed at the spermiation phase. The fiber structure of middle piece was consisted of nine outer doublets and two central singlet microtubules and Nos. 1, 5, 6 and 9 in the outer dense were larger than the others(2, 3, 4, 7, 8).

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.11
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• pp.1477-1486
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• 2009

Female germ cell meiotic divisions are typically asymmetric, giving rise to two daughter cells with different sizes. Spindle movements including spindle migration from the oocyte center to the cortex and spindle rotation from parallel to perpendicular (typically in the mouse) at the cortex are crucial for these asymmetric divisions and therefore are crucial for gamete production. Different regulatory mechanisms for spindle movements have been determined in different species and a wide variety of different molecular components and processes that are involved in spindle movements have also been identified in different species. Here, we review the current state of knowledge as well as our understanding of mechanisms for spindle movements in different systems with focus on three main aspects: microtubules (MT), microfilaments (MF) and molecules associated with cytoskeletal organization as well as molecules that are not directly related to the cytoskeleton. How they might interact or function independently during female meiotic divisions in different species is discussed in detail.

• 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).

• Fisheries and Aquatic Sciences
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• v.8 no.1
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• pp.17-26
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• 2005

The ultrastructure of germ cells during spermatogenesis and the structural changes in the epithelial cells of the seminal vesicle with testicular development in male Neptunea (Barbitonia) arthritica cumingii were investigated monthly based on electron microscopic and histologic observations. N. arthritica cumingii (Gastropod: Buccinidae) undergoes internal fertilization and possesses a modified type of spermatozoon, which is approximately 20$\mu$m long. The axoneme of the tail flagellum consists of nine peripheral pairs of microtubules and one central pair. Many spermatozoa occur in the acini of the testis in the ripe stage and are transported to the seminal vesicles in the accumulating phase. In males, the monthly gonadosomatic index began to increase in September and reached a maximum in February. Subsequently, it decreased rapidly after April. The testis of this species can be classified into four developmental stages: the active (August to September), ripe (October to July), copulation (April to July), and recovery (July to August) stages. Structural changes in the epithelial cells of the seminal vesicles of this species could be classified into three phases: (1) S-I (resting), (2) S-II (accumulating), and (3) S-III (spent) phases. The morphology and structure of the epithelial cells of the seminal vesicle differed in each phase; the cells were cuboidal, squamous, or columnar in the resting, accumulating, or spent phases, respectively.

• Korean Journal of Microbiology
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• v.32 no.1
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• pp.28-33
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• 1994

In normal cells tau protein is associated with axonal microtubules, whereas in Alxheimer's disease it is immobilized in the somatodendritic compartment of certain nerve cells as a major component of the paired helical filament. As a part of the study to analyze the nature of the paired helical filament (PHF) deposits and some related factors in brain, we have cloned and expressed a human tau gene cDNA in Escherichia coli to obtain the recombinant human tau protein in abundance.