• The Korean Journal of Malacology
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• v.26 no.3
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• pp.235-244
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• 2010

Ultrastructural characteristics of the testis and spermatogenesis of Crassostrea gigas were investigated by Transmission and Scanning Electron microscope observations. The testis is a diffuse organ consisting of branching acini containing differentiating germ cells in a variety of stages. The acinus is surrounded by an intermitent layer of myoepithelial cells andis divided into subcompartments that are partially separated by pleomorphic accessory cells which remain in close contact with germ cells until late stages of development. these accessory cells contain a large quantity of glycogen particles and lipid droplets in the cytoplasm. Therefore, it is assumed that they are involved in the supplying of the nutrients for germ cell development, while any phenomena associated with phagocytosis of undischarged, residual sperms by lysosomes could be find in the cytoplasm of the accessory cells. The morphology of the spermatozoon has a primitive type and is similar to those of other bivalves. Mature spermatozoa consist of broad, cap-shaped acrosomal vesicle, subacrosomal material (containing axial rod embedded in a granular matrix), a oval nucleus showing deeply invaginated anteriorly, two triplet substructure centrioles surrounded by four spherical mitochondria, and satelite fibres appear to the distal centriole and plasma membrane. Spermatozoa of C. gigas resemble to those of other investigated ostreids. In particular, the anterior region of the acrosomal vesicle is transversely banded. It is assumed that differences in this acrosomal substructure are associated with the inability of fertilization between the genus Crassostrea and other genus species in Ostreidae. Therefore, we can use sperm morphology in the resolution of taxonomic relationships within the Ostreidea. The spermatozoon is approximately $42-47{\mu}m$ in length including an oval sperm nucleus (about $0.91{\mu}m$ in length), an acrosome (about $0.42{\mu}m$ in length) and tail flagellum ($40-45{\mu}m$). 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. These morphological charateristics of acrosomal vesicle belong to the family Ostreidae in the subclass Pteriomorphia.

• Korean Journal of Animal Reproduction
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• v.21 no.3
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• pp.311-319
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• 1997

This study was carried out to investigate the ultrastructural changes of spermatozoa obtained from 20 of 3-year-old male chum salmon(Oncorhynchus keta) collected and analysed in middle October in 1995. The ultrastructural changes of gonad of fingerlings were examined to describe the sex differentiation of this species. The results obtained in this study were as follows : In spermatozoa, the nucleus is dense and homogeneous. Two spheroidal mitochondria(about 350nm long) are situated in parallel between the nucleus and the axoneme. Spermatozoa mitochondria are assembled into an organized sheath surrounding the outer dense fibres and axoneme of the flagellar midpiece. The sheath flagellum is situated beneath the base of the sperm head. The primordial germ cells of 6.8~7.2${\mu}{\textrm}{m}$ in size, which were buried under fibrous mesenchymal tissue between gut duct and notochord of larva with a total length of 2.4cm at 50 days after hatching. In juvenile of 10.5cm in total length at 70 days after hatching, the gonad was occupied by bundles of oogonia. The dense drumstick bodies(large arrows) are observed in the nuclei of the primordial gonad and surrounding tissue cells of fingerling at 70 days after hatching. The oval Barr bodies(asterisk) are observed in the nuclei of the primordial germ cells under the mitosis(2n). Note the large mitochondria, ribosomes and rough endoplasmic reticulum in the cytoplasm. Accordingly, the fingerlings at 70 days after hatching are identified as the female(xx). In result, the gonadal sex differentiation begins from the 70 days after hatching in chum salmon.

• Journal of Life Science
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• v.15 no.3 s.70
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• pp.387-396
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• 2005

The aims of the study were to establish a short-term screening test for detecting testicular toxicity of chemicals in rats and to determine whether a 2-week administration period is sufficient to detect testicular toxicity of 2-bromopropane (2-BP) as an example. Male Sprague-Dawley rats were subcutaneously administered with 1000 mg/kg/day of 2-BP or its vehicle for 2 weeks. Ten male rats each were sacrificed on days 3, 7 and 14 after the initiation of treatment. Parameters of testicular toxicity included genital organ weights, testicular sperm head counts, epididymal sperm counts, motility and morphology, and qualitative and quantitative histopathologic examinations. The early histopathological changes observed on day 3 of treatment included degeneration of spermatogonia and spermatocytes, multinuclear giant cells, mature spermatid retention, vacuolization of Sertoli cells, and decreased number of spermatogonia in stages II and V. On day 7 of treatment, atrophy of seminiferous tubules, exfoliation of germ cells, degeneration of spermatogonia and spermatocytes, multinuclear giant cells, mature spermatid retention, vacuolization of Sertoli cells, decreased number of spermatogonia in stages II and V, and decreased number of spermatocytes in stages VII and XII. On day 14 after treatment, a significant decrease in the weights of testes and seminal vesicles was found. Atrophy of seminiferous tubules, exfoliation of germ cells, degeneration of spermatogonia and spermatocytes, mature spermatid retention, vacuolization of Sertoli cells, decreased number of spermatogonia in stages II and V, and decreased number of spermatocytes in all spermatogenic stages were also observed. In addition, a slight non-significant decrease in testicular sperm head counts, daily sperm production rate and epididymal sperm counts was found. The results showed that 2 weeks of treatment is sufficient to detect the adverse effects of 2-BP on male reproductive organs. It is considered that the short-term testicular toxicity study established in this study can be a useful tool for screening the testicular toxic potential of new drug candidates in rats.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.9
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• pp.1227-1231
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• 2002

A powerful tool for chicken transgenesis could be established by employing a germline chimera production through primordial germ cell transplantation. This study was conducted to examine whether foreign gene-transfected gonadal primordial germ cells (gPGCs) have a migration activity into the gonad after transfer to recipient embryos. In Experiment 1, gPGCs of Korean Ogol Chicken were retrieved from 5.5-day-old embryos and subsequently transferred to the dorsal aorta of 2.5-day-old White Leghorn embryos after being labeled with PKH26 fluorescent dye. To confirm migration activity after transplantation, recipient embryos were sacrificed and examined on 3 days after transfer. Sex determination was concomitantly undertaken to examine whether sex of recipient embryos could affect the migration activity of gPGCs. All of embryonic gonads examined showed positive signals with PKH26 fluorescence and W-chromosome specific band by polymerase chain reaction (PCR) was detected in male embryos when gPGCs with ZW chromosome were transferred to recipient embryos. In Experiment 2, retrieved gPGCs were transfected with LacZ gene-containing cytomegalovirus promoter ($pCMV{\beta}$) by electroporation and subsequently transferred to recipient embryos. LacZ gene expression was identified in the gonads of 6 or 10-day-old recipient embryos and hatched-chicks. A total of 20 embryos and 12 hatched-chicks were examined and 11 of them (10 embryos and one hatched chicken; 11/32=34.4%) expressed $\beta$-galactosidase, a marker substance of LacZ gene. The results of this study demonstrated that foreign gene-transfected gPGCs can migrate and settle down into the gonad after being transferred into the blood vessel of the recipient embryos. This established technique will contribute to developing a peer biotechnology for transgenic chicken.

• Korean Journal of Poultry Science
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• v.23 no.1
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• pp.1-7
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• 1996

In order to produce polyploid quail, the patterns of spermatogenesis and induction of diploid spermatozoa were analyzed by administration of spindle fiber inhibitor agent. Colcemid at the dose level of 37 $\mu\textrm{g}$ /100 g BW was Injected intraperitoneally to 50 Japanese quail males for 3 consecutive days. Five to 20 days after the first colcemid injection, the metaphase spreads from mitotic spermatogonia, primary spermatocyte and secondary spermatocyte were observed. By cytogenetic analysis, 9.4％ of spermatogonia and spermatocyte cells in germ cells from the treated males was found to be polyploid cells. As compared with colcemld treated, the males with non-treated colcemid had only 2.3％ polyploid cells in germ cells. The induction of diploid germ cells was highest in 10 days after the first colcemid injection and was lowest in 5 days after the first colcemid injection. These results suggested that between 10 to 15 days before maturation of the spermatozoa, the male germ cells were most sensitive to colcemid treatment. Spindle fiber inhibitor agent was also more sensitive to mitotic division of spermatogonia than meiotic division of primary and secondary spermatocyte.

• Development and Reproduction
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• v.21 no.3
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• pp.237-247
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• 2017

Mammalian spermatogenesis occurs in a precise and coordinated manner in the seminiferous tubules. One of the attempts to understand the detailed biological process during mammalian spermatogenesis at the molecular level has been to identify the testis specific genes followed by study of the testicular expression pattern of the genes. From the subtracted cDNA library of rat testis prepared using representational difference analysis (RDA) method, a complimentary DNA clone encoding type III member of a DnaJ family protein, DnaJC18, was cloned (GenBank Accession No. DQ158861). The full-length DnaJC18 cDNA has the longest open reading frame of 357 amino acids. Tissue and developmental Northern blot analysis revealed that the DnaJC18 gene was expressed specifically in testis and began to express from postnatal week 4 testis, respectively. In situ hybridization studies showed that DnaJC18 mRNA was expressed only during the maturation stages of late pachytene, round and elongated spermatids of adult rat testis. Western blot analysis with DnaJC18 antibody revealed that 41.2 kDa DnaJC18 protein was detected only in adult testis. Immunohistochemistry study further confirmed that DnaJC18 protein, was expressed in developing germ cells and the result was in concert with the in situ hybridization result. Confocal microscopy with GFP tagged DnaJC18 protein revealed that it was localized in the cytoplasm of cells. Taken together, these results suggested that testis specific DnaJC18, a member of the type III DnaJ protein family, might play a role during germ cell maturation in adult rat testis.

• Proceedings of the KSAR Conference
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• 2003.06a
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• pp.97-97
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• 2003

For many animals the centrosome consists of a pair of centrioles and surrounding pericentriolar materials (PCMs). PCMs have been known to play roles during cell division. It is known that centrioles are necessary to assemble centrosomal components. However, many types of oocytes undergo meiosis without centrioles. It is known that in nonmurine mammalian species, the sperm introduces an intact proximal centriole unlike sea urchin where two centrioles are introduced. In case of mouse sperm, the presence of centrosome is not clear In this study, a monoclonal antibody was developed to investigate centrosome during mouse germ cell and early embryo development. Results of immunostaining and Western blotting in CHO cells suggest that the monoclonal antibody recognizes a nuclear and centrosomal protein, thus called NCP. The NCP monoclonal antibody was used to screen a cDNA expression library prepared from 12.5 mouse brain to isolate NCP gene. Nucleotide size of NCP gene obtained from immunoscreening was about 5.5kb. It is determined that the NCP may be closely related with pericentriolar material -1 gene (Pcm-1) from the result of sequencing analysis. The molecular weight, 66kDa, calculated by known DNA sequence in database is consistent with that of detected from Western blotting using CHO cell lysates. Therefore, it is assumed that NCP may be alternative splicing form of Pcm-1 of which molecular weight is 228kDa. In mouse oocytes, NCP was distributed in nucleus as in CHO cells. It was shown that the NCP was localized around neck region, probably the centrosome in mouse neck region. Interestingly, dramatic change in distribution of NCP was also shown in male germ cell development. Finally, we observed the cellular distribution of NCP during early embryo development. NCP was detected in nucleus as well as centrosome foci. It is suggested that the centrioles reassembly we occurring in blastocysts and then affects the distribution of NCP.

• Proceedings of the Zoological Society Korea Conference
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• 1996.10a
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• pp.151.1-151
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• 1996

No Abstract, See Full Text

• 대한생식의학회:학술대회논문집
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• 2002.05a
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• pp.72-73
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• 2002

• 대한생식의학회:학술대회논문집
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• 1999.11a
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• pp.50.2-51
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• 1999