• Development and Reproduction
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• v.17 no.2
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• pp.121-132
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• 2013

Ultrastructural characteristics of the germ cells and accessory cells in testis during spermatogenesis and taxonomic values of mature sperm morphology of Ruditapes philippinarum were investigated by the transmission electron microscope and scanning electron microscope observations. The testis is the diffuse organ that consists of branching acini containing developing germ cells and accessory cells associated with spermatogenesis. The morphology of the spermatozoon is of the primitive type and is somewhat different to those of other bivalves. The morphologies of the sperm nucleus type and the acrosome shape of this species have a cylinderical type and a modified cone shape, respectively. As some ultrastructural characteristics of the acrosomal vesicle, the peripheral parts of two basal rings show electron opaque part, while the apex part of the acrosome shows electron lucent part. These characteristics of sperm belong to the family Veneridae in the subclass Heterodonta, unlike a characteristic of the subclass Pteriomorphia showing all part of the acrosome being composed of electron opaque part. In particular, a cylinder-like nucleus of the sperm is curved. The spermatozoon is approximately $48-51{\mu}m$ in length, including a long acrosome (about $2.4{\mu}m$ in length), a curved sperm nucleus (about $3.40{\mu}m$ in length), and a tail flagellum. The axoneme of the sperm tail shows a 9+2 structure.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.3
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• pp.171-175
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• 2000

The ultrastructures of germinal cells of male marsh clam, Corbicujar lena were studied. The mature sperm was primitive type, consisting of head, middle piece and tail. The mature sperm was whip-shaped and its head was divided into two parts; the acrosomal part shaped long hollow cone about $3{\mu}m$ in length and the sperm nuclear part shaped a long stick about $9\;{\mu}m$ in length. The posterior part of the sperm nuclear projected to centriole, The middle piece of the sperm-nuclear had four mitochondria and two centrioles. The sperm tail part had the 9+2 microtubular arrangement known as a typical pattern, During spermiogenesis, chromatin within sperm nuclear became fiberic materials by condensation.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.6
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• pp.755-759
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• 2004

The present investigation was carried out to assess the effect of Sephadex (G-15) filtration on the post thaw bull semen quality and conception rate. Post thaw unfiltered (control) and Sephadex filtered semen from four healthy bulls (three cross bred and one pure bred Holstein Friesian) were subjected to microscopic examination viz. sperm concentration, individual motility, live sperm count and sperm morphology. Sixty-two healthy, normal cycling crossbred cows were inseminated with post thaw unfiltered (n=32) and filtered semen (n=30). Sephadex filtration of post thaw semen significantly (p<0.05) decreased total sperm concentration and sperm with abnormal head, mid piece and tail. The overall average total sperm concentration, head and tail defects in filtered semen decreased significantly (53.4, 1.2 and 6.4 million) than in the unfiltered semen (80.4, 2.4 and 15.7 million, respectively). However, after filtration significant (p<0.05) increase in overall average motile and live sperm concentration were observed (38.8 and 38.0) as compared to unfiltered semen (29.2 and 32.0 million, respectively). The overall conception rate recorded was 21.9% with post thaw unfiltered semen and 56.7% with filtered semen. It was concluded that Sephadex filtration of post thaw semen improved its quality and conception rate.

• 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).

• Animal cells and systems
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• v.11 no.2
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• pp.227-234
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• 2007

Spermatogenesis, the reproductive cycle, and the size at first sexual maturity in male Mactra chinensis were investigated by cytological and histological observations. The spermatozoon exhibits a primitive type morphology and is similar to those of other bivalves in that it contains a short midpiece with four mitochondria surrounding the centrioles. The morphologies of the sperm nucleus type and the acrosome shape of this species are cylindrical and modified cap-like, respectively. The spermatozoon is approximately $40-45\;{\mu}m$ in length including the sperm nucleus (about $1.46\;{\mu}m$), acrosome (about $1.20\;{\mu}m$) 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 this species lasts from June to September, and the main spawning occurs in July and August, when the seawater temperature is greater than $20^{\circ}C$. The percentage of individual male clams at first sexual maturity was 56.5% for those whose shell lengths were 35.1-40.0 mm, and 100% for over 45.1 mm. Accordingly, harvesting clams <35.1 mm in shell length could potentially cause a drastic reduction in recruitment, and a measure indicating a prohibitory fishing size should be taken for adequate fisheries management.

• Parasites, Hosts and Diseases
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• v.22 no.1
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• pp.30-36
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• 1984

An ultrastructural study on the mature spermatoBoa oi Cloptorchis sineitsis was carried out. For this study, the liver cukes were collected from the livers of rabbits and rats artificially infected with the metacercariae obtained from the fresh water fish, Pseudorasbora parve. Six-month old worms were used. The collected liver fiukes were washed with 0.85% saline solution and then immediately moved to cold 2% glutaraldehyde buffered with 0.1M Millonig's phosphate buffier (pH 7.4) . The materials were dissected into appropriate pieces in the fixative about 30 minutes after beginning of the fixation. Two hours later the materials containing the seminal receptacle were rinsed several times with the buffier and were secondarily fixed with cold, bugeyed 1% osmium tetroxide(OsO4) for 2 hours. The fully mixed tissue blocks Ivere dehydrated in a series of graded concentrations of acetone and were embedded in Epon 812 mixture. Thin sections obtained from LKB-5 ultramicrotome were stained with uranyl acetate and Reynold's lead citrate. Observations of the sections were carried out with JEM-100CX II electron microscope, In general, the mature sperm was long thread-like form with a sickle-shaped head. According to the longitudinal sectioned view of the sperm tail, the nucleus seemed to be spirally coiled and run a little far along the tail. The acrosome was not observed. The cytoplasm of the tail was biflagellated as usual in trematodes. Unlike other platyhelminth spermatozoa, the sperm tail of Clenorchis sinensis showed the ${\ulcorner}9+2{\lrcorner}$ in the microtubular arrangement. The mitochondria with poorly developed cristae were observed throughout the middle piece. The middle piece of the tail showed dull ladder or triangular shapes with the two flagella at the bottom. But, the principal piece of the tail was slightly flattened cylindrical shape with two aagella within the cytoplasm. The end piece was uniflagellated. It was not clearly identised whether the end piece was subdivided into two by aagellum or the lengths of the two aagella were different. The glycogen granules were rich in the cytoplasm throughout the lenght of the spermatozoa. These granules might be the energy source for the movement of the spermatosoa.

• The Korean Journal of Malacology
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• v.30 no.3
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• pp.211-218
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• 2014

Spermatid differentiations during spermiogenesis and sperm ultrastructures in male Mercenaria stimpsoni 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, become 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 cap shape, respectively. The spermatozoon is approximately $48-51{\mu}m$ in length including a curved cylinderical sperm nucleus (about $4.18{\mu}m$ long), an acrosome (about $0.52{\mu}m$ in length) and tail flagellum ($42-45{\mu}m$ 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 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 $80^{\circ}$), as seen in some species of Veneridae (range from $0^{\circ}$ to $80^{\circ}$). 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 Korean Journal of Malacology
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• v.28 no.1
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• pp.55-64
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• 2012

Ultrastructural studies of germ cell development during spermatogenesis and taxonomic values in mature sperm morphology of Argopecten irradians irradians were investigated by transmission electron microscopic observations. In the early stage of spermatid during spermiogenesis, a few granules and proacrosomal granules are formed by the Golgi complex. In the late stage of spermatid during spermiogenesis, a proacrosomal vesicle becomes an acrosomal vesicle in the acrosome through spermiogenesis. The sperm is approximately $ 45-48{\mu}m$ in length including a jar-shaped sperm nucleus (about $1.45{\mu}m$ long), an acrosome (about $0.34{\mu}m$ long) and tail flagellum. The axoneme of the sperm tail shows a 9+2 structure. As one of common characteristics of mature sperm morphologies in Pectinidae species in subclass Pteriomorphia, mature spermatozoon consists of the cone-shaped acrosomal vesicle and subacrosomal material on the invaginated jar-shaped nucleus. The acrosomal vesicle of this species is composed of electron high dense opaque part (material) from the base to the tip, as have seen in the species in the subclass Pteriomorphia. Exceptionally, five mitochondria are found in the sperm midpiece of this species, unlike four in most species of Pectinidae in subclass Pteriomorphia. However, the acrosomal vesicle of spermatozoa of A. irradians irradians resemble to those of other investigated Pectinidae species in subclass Pteriomorphia. Therefore, we can use sperm morphology as a tool in the resolution of taxonomic relationships within the Pectinidae species. These morphological charateristics of acrosomal vesicle belong to the family Pectinidae in the subclass Pteriomorphia.

• The Korean Journal of Malacology
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• v.22 no.2
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• pp.115-124
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• 2006

Gonad index, spermatogenesis and the reproductive cycle of Meretrix petechialis were investigated by cytological, histological observations. Monthly changes in the gonad index coincides the gonadal development. The morphology of the spermatozoon had a primitive type and is similar to that of other bivalves having a short mid-piece with five to six mitochondria surrounding the centrioles. The morphology of the sperm nucleus type and the acrosome shape of this species were cylindrical type and cap-like shape, respectively. The spermatozoon was approximately 40-45 ${\mu}m$ in length including the sperm nucleus length (about 1.50 ${\mu}m$), acrosome length (0.60 ${\mu}m$) and tail flagellum. The axoneme of the tail flagellum consisted of nine pairs of microtubules at the periphery and a pair at the center. The axoneme of the sperm tail showed 9 + 2 microtubular arrangement. The spawning period was from June to September and the main spawning occurred from July to August when seawater temperatures were higher than $20^{\circ}C$. The reproductive cycle of this species could be categorized into five successive stages: early active stage (February to March), late active stage (February to May), ripe stage (April to July), partially spawned stage (June to September), and spent/inactive stage (September to February).

• Journal of Embryo Transfer
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• v.27 no.1
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• pp.21-28
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• 2012

A study was conducted on four crossbred bulls, used as artificial insemination (AI) sires, to correlate their semen quality with their non return rate (NRR). Semen was collected once a week via an artificial vagina, diluted in egg yolk-citrate and maintained at $+7^{\circ}C$ for three days. It was evaluated for sperm motility, viability, morphology immediately after collection and was examined daily for sperm motility, viability and morphology of acrosome, mid piece and tail for a total of three days. A total of 2016 cows were inseminated by two AI technicians. The proportions of sperm with normal heads were 83.4% (63.7~91.7%), the proportion of spermatozoa exhibiting normal morphology (acrosome, mid piece and tail), motility and viability were 89.2% (82.3~92.0%), 71.3% (61.7~75.0%) and 76.7% (65.7~85.0%), respectively in fresh ejaculates. Sperm motility and sperm viability was significantly ($p$ <0.05) lower in Holstein-Friesian ${\times}$ Local bull than in other bulls during all three days of storage. The overall NRR for four bulls was 82.7% (72.9-87.5%). Bulls with higher sperm motility, viability and normal morphology of spermatozoa of individual bull had significantly (each $p$ <0.05) higher NRR. The highest ($p$ <0.01) NRR (87.5%) was observed in a Red Chittagong bull whose semen qualities were significantly ($p$ <0.05) higher than Holstein-Friesian ${\times}$ Local bull (NNR 72.9%). The results of the present study concluded that NRR at 56 days post AI is related to parameters of semen quality. Therefore, semen evaluation may allow the discarding of bulls with poor fertility in an AI program.