• The Korean Journal of Malacology
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• v.22 no.1 s.35
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• pp.39-49
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• 2006

Ultrastructure of germ cell differentiation during supermatogenesis and the reproductive cycle in male Patinopecten yessoensis was studied by histological and cytological observations. The gonadosomatic index (GSI) in males rapidly increased and reached a maximum in April when seawater temperature gradually increased. Then the GSI gradually decreased from May through July when spawning occurred. Accordingly, monthly changes in the GSI in males coincided with testicular maturation and spawning periods. The sperm morphology of P. yessoensis belongs to the primitive type and showed general characteristics of external fertilization species. The head of the spermatozoon is approximately $3.50{\mu}m$ in length: the sperm nucleus and acrosome are approximately $2.90{\mu}m\;and\;0.60{\mu}m$ in length, respectively. The nuclear type of the spermatozoon is vase in shape, and the acrosome is cone type. The axoneme of the tail flagellum consists of nine pairs of microtubules at the periphery and a pair of central microtubules in the center The satellite body (which is formed by the centriole) and four mitochondria appear in the middle piece of the spermatozoon. The spawning period was from April through July and the main spawning occurred from May to June when seawater temperatures gradually increased. The reproductive cycle of this species can be classified into five successive stages; early active stage (September to November), late active stage (October to March), ripe stage (February to August), spawning stage (April to July), and spent/inactive stage (July to November).

• Development and Reproduction
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• v.11 no.2
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• pp.97-104
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• 2007

This study describes the spermatogenesis and sperm ultrastructure of the spiny top shell, Batillus cornutus using light and electron microscopy. The spiny top shells were collected by divers in the coastal water of Wandogun, Cheollanamdo, Korea(N $34^{\circ}13'$, E $126^{\circ}47'$) at May 2003. Spiny top shells of $60.0{\sim}69.9\;mm$ in shell height were used in this study. The testis comprises many spermatogenic follicles which contains germ cells in different developmental stages. The primary spermatocytes in the pachytene stage were characterized by synaptonemal complexes. The early spermatids were characterized by appearance of Golgi complex, increased karyoplasmic electron density and tubular mitochondria. In early spermatid the mass of proacrosomal granules consists of numerous heterogeneous granules with high electron density. From the mid-stage of spermiogenesis the well-developed mitochondria aggregate posterior to the nucleus, and surround the proximal and distal centrioles. In this stage, proacrosomal granules are condensed and form a acrosome with thin envelope. During the late spermiogenesis, the acrosome begins to elongate and then became conical. The sperm consists of head, mid-piece and tail. The head comprises a round nucleus and a conical acrosome. Acrosomal rod of microfibrous is observed between nucleus and acrosome. Five mitochondria observed in mid-piece. And tail has the typical "9+2" microtubular system originates from the centrioles.

• Development and Reproduction
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• v.1 no.2
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• pp.133-139
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• 1997

To study the function and structure of Golgi apparatus in the spermiogenesis of long-fingered bat (Miniopterus schreibersi fuliginosus), the testis obtained from adult bat was treated with the prolonged osmification or fixed with ferrocyanide reduced osmium. golgi apparatus was oval shape in early Golgi phase, and was composed of cortex and medullar enclosing acrosome in mid Golgi phase. The vesicles of crescent shape Golgi apparatus were closed or fused with small or large vesicles at the periphery of acrosome. Golgi apparatus moved behing the acrosome face in cap phase, but the Golgi apparatus was still active. According to this, Golgi apparatus appears to be involved in the formation of acrosome and sperm tail. Transfer of materials from Golgi to acrosme seems to be carried out not only by fusion of large vesicles with acrosomal vesicles but also by detachment of coated vesicle from various cisternae of Golgi fusing with acrosomal vesicle.

• Applied Microscopy
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• v.40 no.1
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• pp.1-8
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• 2010

The ultrastructure of spermatogenesis and sperm in Chinese minnow, Rhynchocypris oxycephalus belonging to Leuciscinae was investigated by light and electron microscopes. The whitish testis was located between intestine and air bladder. The size of testis was major axis 2.3 cm, minor axis 6 mm. The testis contained numerous testicular cysts, and spermatogenesis was non-synchronized in these testicular cysts. In the case of spermatogonium, the nucleus was comparatively large ellipsoidal, and mitochondria showed a marked development. The size of primary spermatocyte was smaller than that of spermatogonia, and secondary spermatocyte was smaller than primary spermatocyte. The chromatin of spermatocyte was highly condensed according to their development. The nucleus with electron-dense was round shape. In spermiogenesis, flagella started to be formed and chromatin was more condensed. The mitochondria were rearranged in a middle piece. The sperm was formed by loss of cytoplasm. The head of mature sperm was a spherical shape and have not acrosome. The microtubules of flagella were arranged 9+2 structure. Also, the tail of sperm have not lateral fins.

• Applied Microscopy
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• v.39 no.3
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• pp.219-226
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• 2009

The ultrastructure of spermatogenesis and sperm in Cichlasoma managuensis belonging to Cichlidae was investigated by light and electron microscopes. The testis of C. managuensis contained numerous testicular cysts, and spermatogenesis was synchronized in these testicular cysts. In the case of spermatogonia, the nucleus was comparatively large ellipsoidal, and mitochondria showed a marked development. The size of primary spermatocyte was smaller than that of spermatogonia, and that of secondary spermatocyte was smaller than that of primary spermatocyte. The chromatin of spermatocyte was highly condensed according to their development. The nucleus with electron-dense was round shape. In spermiogenesis, flagella started to be formed and chromatin was more condensed. The mitochondria were rearranged in a middle piece. The sperm was formed by loss of cytoplasm. The head of mature sperm was a spherical shape and had not acrosome. The microtubules of flagella were arranged 9+2 structure. Also, the tail of sperm have lateral fins.

• 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.

• The Korean Journal of Malacology
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• v.21 no.2 s.34
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• pp.95-105
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• 2005

Gonadosomatic index, reproductive cycle, spermatogenesis and first sexual maturity of Chlamys farreri were investigated by cytological and histological observations, from January 1998 to December 1999. The gonadosomatic index (GSI) rapidly increased in April and reached a maximum in May when seawater temperature rapidly increase. Then the GSI gradually decreased from June to August when spawning occur. Accordingly, monthly changes in the GSI in males coincide with the reproductive cycle. The spermatozoon of Chlamys farreri is the primitive type found in external fertilization species. The head of the spermatozoon is approximately $2.75{\mu}m$ in length including the acrosome measuring about $0.50{\mu}m$ in length, and its tail was approximately $20{\mu}m$, the axoneme of the tail flagellum consists of nine pairs of microtubules at the periphery and a pair at the center. Five spherical mitochondria around the centriole (the satellite body) appear in the middle piece of the sperm. The spawning period was from June to August and the main spawning occurs from July to August when seawater temperatures are greater than $20^{\circ}C$ The reproductive cycle of this species can be categorized into five successive stages; early active stage (January to March), late active stage (March to April), ripe stage (April to August), partially spawned stage (June to August), and spent/inactive stage (August to January). Over 50% of male scallops attained first sexual maturity between 50.0 and 60.0 mm in shell height, and 100% of those over 60.0 mm in shell height achieved maturity. Accordingly, we assume that male individuals begin reproduction at three years of age.

• 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).

• Development and Reproduction
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• v.2 no.2
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• pp.141-148
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• 1998

The fine structure of spermatozoa of Pungtungia herzi was examined with scanning and transmission electron microscopies. The spermatozoa of p. herzi are approximately 37.4 ${\mu}{\textrm}{m}$ in length and a relatively simple cell with a spherical nucleus, a short midpiece and a tail. The acrosome is not present as in most teleost fishes. The ultrastructure of spermatozoa represents typical characteristics of cyprinid spermatozoa including the lateral insertion of flagellum, the organization of centriolar complex in shallow nuclear fossa, and the occurrence and asymmetrical arrangement of mitochondria. In the nuclear envelope and mitochondrion, however there were some morphological differences for their ultrastructure. The nuclear envelope is severely undulated and the shallow nuclear fossa contains two centrioles which are at the angle of some 130$^{\circ}$ each other. The most significant feature can be observed with the mitochondrion; five or more mitochondria, which are shown in primary spermatocyte, fuse to form a single one in the mature spermatozoon. The mitochondrial aspect is different from that of other cyprinid spermatozoa, where their mitochondria have a conventional aspect and never fuse to form a mitochondrial derivative. In terms of sperm evolution the fused mitochondria are regarded as the apomorphic character in comparison with the separate mitochondria. The single mitochondrion is not reported in cyprinid spermatozoon except the case of Rhodeus.

• BMB Reports
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• v.41 no.9
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• pp.664-669
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• 2008

Znf230, the mouse homologue of the human spermatogenesis-related gene, ZNF230, has been cloned by rapid amplification of cDNA ends (RACE). This gene is expressed predominantly in testis, but its expression in different testicular cells and spermatogenic stages has not been previously analyzed in detail. In the present study, the cellular localization of the Znf230 protein in mouse testis and epididymal spermatozoa was determined by RT-PCR, immunoblotting, immunohistochemistry and immunofluorescence. It is primarily expressed in the nuclei of spermatogonia and subsequently in the acrosome system and the entire tail of developing spermatids and spermatozoa. The results indicate that Znf230 may play an important role in mouse spermatogenesis, including spermatogenic cell proliferation and sperm maturation, as well as motility and fertilization.