Two states of active spermatogenesis switch between reproductive and non‐reproductive seasons in the testes of the medaka, Oryzias latipes

Iwasaki, Yuko; Ohkawa, Keiko; Sadakata, Hisato; Kashiwadate, A.; Takayama‐Watanabe, Eriko; Onitake, Kazuo; Watanabe, Akihiko

doi:10.1111/j.1440-169x.2009.01114.x

Cited by 11 publications

(8 citation statements)

References 35 publications

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“…A previous study suggested that testicular germinal epithelial cells in rodents are especially susceptible to cytotoxic drugs because testicular germinal epithelial cells have high mitotic activity 23 . Spermatogonia and spermatocytes in medaka testes also show high cell proliferative activity 25 , and this finding may be related to the induction of apoptosis in spermatogonia and spermatocytes in medaka testes exposed to MTX in the present study.…”

Section: Discussionsupporting

confidence: 58%

Effects of methotrexate exposure on medaka (Oryzias latipes) testes

et al. 2017

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For the purpose of clarifying the histopathological effects of methotrexate (MTX) on medaka testes, wild-type and homogenic p53-deficient male medaka at 4 to 6 months post-hatching were exposed to 0.25 mg/ml of MTX for 96 h with histopathological examination of testes at 24, 48, 72 and 96 h. At 72 and 96 h after the start of MTX exposure, numerous apoptotic cells were observed in the spermatogonia and spermatocytes, and the pyknotic cell rate and the TUNEL-positive and cleaved caspase-3-positive rates in the spermatogonia and spermatocytes of MTX-treated wild type medaka were higher compared with those in the control wild-type medaka. Starting at 48 h, the phospho-histone H3-positive rate in the spermatogonia and spermatocytes of was significantly lower in MTX-treated wild-type medaka than in control wild-type medaka. In homogenic p53-deficient medaka, apoptosis was not induced in the spermatogonia and spermatocytes by exposure to MTX. Starting at 48 h, the phospho-histone H3-positive rate in spermatogonia and spermatocytes of MTX-treated homogenic p53-deficient medaka was lower than in control homogenic p53-deficient medaka. Throughout the entire experimental period, there were no significant differences in phospho-histone H3-positive rates in the spermatogonia and spermatocytes between the MTX-treated homogenic p53-deficient medaka group and the MTX-treated wild-type medaka group. In the present study, spermatogonia and spermatocytes of medaka testes were sensitive to MTX at 0.25 mg/ml in the culture water, and MTX-induced apoptosis in the testes was dependent on p53 expression; however, inhibition of MTX-induced cell proliferation was independent of p53 expression.

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Section: Discussionsupporting

confidence: 58%

Effects of methotrexate exposure on medaka (Oryzias latipes) testes

et al. 2017

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“…In these two species and other seasonal fish, FSH seems to be more involved in early spermatogenesis comprising the spermatogonial stages and LH plays the main role during the maturing process of future sperm (10,73,74). As discussed in section "7-Day Culture of Testis Explants Requires Addition of tilPE for Maintenance of Intact Testis structure" above, an influence of FSH on spermatogonial proliferation is also reported from non-seasonal fish like medaka and zebrafish (5,26,48,49). Future studies should investigate differential transcriptional activation of steroidogenesis-related genes by LH and FSH.…”

Section: Gene Expression Of the Leydig Cell Markers Star2 And Cyp11b2mentioning

confidence: 85%

“…In zebrafish, germ cell proliferation was successfully increased by recombinant FSH under tissue culture conditions (48). Also using testis culture, the proliferation of SgA and SgB could be maintained up to 10 days in medaka by adding human FSH (49). In amphibians like the newt Cynops pyrrhogaster FSH has also been studied in regard of its role in spermatogonia proliferation.…”

Section: -Day Culture Of Testis Explants Requires Addition Of Tilpe mentioning

confidence: 99%

An ex vivo Approach to Study Hormonal Control of Spermatogenesis in the Teleost Oreochromis niloticus

et al. 2020

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As the male reproductive organ, the main task of the testis is the production of fertile, haploid spermatozoa. This process, named spermatogenesis, starts with spermatogonial stem cells, which undergo a species-specific number of mitotic divisions until starting meiosis and further morphological maturation. The pituitary gonadotropins, luteinizing hormone, and follicle stimulating hormone, are indispensable for vertebrate spermatogenesis, but we are still far from fully understanding the complex regulatory networks involved in this process. Therefore, we developed an ex vivo testis cultivation system which allows evaluating the occurring changes in histology and gene expression. The experimental circulatory flow-through setup described in this work provides the possibility to study the function of the male tilapia gonads on a cellular and transcriptional level for at least 7 days. After 1 week of culture, tilapia testis slices kept their structure and all stages of spermatogenesis could be detected histologically. Without pituitary extract (tilPE) however, fibrotic structures appeared, whereas addition of tilPE preserved spermatogenic cysts and somatic interstitium completely. We could show that tilPE has a stimulatory effect on spermatogonia proliferation in our culture system. In the presence of tilPE or hCG, the gene expression of steroidogenesis related genes (cyp11b2 and stAR2) were notably increased. Other testicular genes like piwil1, amh, or dmrt1 were not expressed differentially in the presence or absence of gonadotropins or gonadotropin containing tilPE. We established a suitable system for studying tilapia spermatogenesis ex vivo with promise for future applications.

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“…We speculate that those s-males were highly suppressed over a long time and such individuals should have low FSH plasma levels (Weltzien et al 2004, Levavi-Sivan et al 2010, Schreck 2010. FSH seems to be necessary for gonial proliferation and has antiapoptotic activity on germ line cells in fish (Ohta et al 2007, Iwasaki et al 2009, Garcia-Lopez et al 2010. …”

Section: Social Hierarchy and Spermatogenesis In D-and S-malesmentioning

confidence: 99%

The social status of the male Nile tilapia (Oreochromis niloticus) influences testis structure and gene expression

Pfennig¹,

Kurth²,

Meißner³

et al. 2012

Reproduction

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Dominant and territorial behaviour are known social phenomena in cichlids and social stress influences reproduction and growth. The gonadotropic hormones trigger spermatogenesis and subordinate males have typically lower levels of gonadotropins than dominant males. In this study, we compared testis morphology and gene expression of dominant and subordinate Nile tilapia males (d-and s-males) in socially stable communities. The d-males had the highest gonadosomatic index but they were not the largest animals in the majority of studied cases. Long-term d-males showed large groups of Leydig cells and hyperplasia of the tunica albuginea due to numerous cytochrome-P450-11b-hydroxylase (Cyp11b) expressing myoid cells. Increased Cyp11b expression in d-males was reflected by elevated 11-ketotestosterone plasma values. However, immunofluorescence microscopy and expression analysis of selected genes revealed that most s-males conserved their capability for spermatogenesis and are, therefore, ready for reproduction when the social environment changes. Moreover, in s-males gene expression analysis by quantitative RT-PCR showed increased transcript levels for germ line-specific genes (vasa, sox2 and dmc1) and Sertoli-specific genes (amh, amhrII and dmrt1) whereas gene expression of key factors for steroid production (sf1 and cyp11b) were reduced. The Nile tilapia is a promising model to study social cues and gonadotropic signals on testis development in vertebrates.

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Two states of active spermatogenesis switch between reproductive and non‐reproductive seasons in the testes of the medaka, Oryzias latipes

Cited by 11 publications

References 35 publications

Effects of methotrexate exposure on medaka (<i>Oryzias latipes</i>) testes

Effects of methotrexate exposure on medaka (<i>Oryzias latipes</i>) testes

An ex vivo Approach to Study Hormonal Control of Spermatogenesis in the Teleost Oreochromis niloticus

The social status of the male Nile tilapia (Oreochromis niloticus) influences testis structure and gene expression

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