Gonadal Development in Fish

Nishimura, T.; Tanaka, Minoru

doi:10.1159/000364924

Cited by 86 publications

(56 citation statements)

References 57 publications

(78 reference statements)

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“…Within each lobule, sox9b -expressing cells surrounding the same stage of spermatogenic cells form a developmental unit referred to as a cyst [Grier, 1981;Nakamura et al, 2011;Nishimura and Tanaka, 2014]. The different stages of these units in the lobule are arranged in a distal (peripheral)-proximal (central) direction such that cysts with germline stem cells/spermatogonia are located at the most distal tip of the lobules, and the cysts with spermatocytes are positioned proximal to the germline stem cell cysts.…”

Section: Comparison Of Wild-type Testes and Foxl3 Mutant Ovariesmentioning

confidence: 99%

“…1 ) and shares the function of the maintenance of germline stem cells in these organs. During early sex differentiation, sox9b -expressing cells surrounding germ cells are a main part of the gonadal primordium [Nakamura et al, 2008;Nishimura and Tanaka, 2014]. Therefore, we investigated when and how the basement membrane appears in the gonadal primordium to form the unit.…”

Section: A Common Unit Found In Ovaries and Testesmentioning

confidence: 99%

“…In medaka, germline stem cells and sox9b -expressing cells are present in both ovaries and testes [Nakamura et al, 2010]. Higher expression of sox9b is observed in the supporting cells enclosing germline stem cells/gonial cells than those surrounding germ cells at an advanced gametogenetic stage [Nakamura et al, 2011;Nishimura and Tanaka, 2014]. Furthermore, deletion of sox9b leads to the loss of germ cells in both males and females [Nakamura et al, 2012].…”

Section: Comparison Of Gonadal Structures Between Medaka and Amniotesmentioning

confidence: 99%

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A Structurally and Functionally Common Unit in Testes and Ovaries of Medaka (Oryzias latipes), a Teleost Fish

Nishimura

Nakamura

Tanaka³

2016

Sex Dev

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Testes and ovaries are structurally and functionally different organs, but they originate from the same gonadal primordium. Here, we propose how a tissue composed of germ cells and sox9b-expressing cells underlain by a basement membrane develops a functionally common unit that reserves sexually indifferent or unfixed germline stem cells in both the ovaries and testes of adult medaka. During testicular development, the unit expands and gives rise to lobules where germline stem cells continuously produce a tremendous amount of sperm, while the unit in the female becomes germinal cradles that represent niche areas for neo-oogenesis. A recent finding in female foxl3 mutants demonstrates that the unit can also serve as the niche for germline stem cells continuously producing sperm in the ovary. We hypothesize that this unit in medaka might correspond to the medullary cords of the gonadal primordium in amniotes and that fragmentation of the medullary cords during ovarian development may be related to the absence of germline stem cells.

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Section: Comparison Of Wild-type Testes and Foxl3 Mutant Ovariesmentioning

confidence: 99%

Section: A Common Unit Found In Ovaries and Testesmentioning

confidence: 99%

Section: Comparison Of Gonadal Structures Between Medaka and Amniotesmentioning

confidence: 99%

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A Structurally and Functionally Common Unit in Testes and Ovaries of Medaka (Oryzias latipes), a Teleost Fish

Nishimura

Nakamura

Tanaka³

2016

Sex Dev

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“…In many organisms, progenitor cells undergo successive and synchronous mitoses, followed by entry into the first events of meiosis, the meiotic prophase I 25, 26, 27, 28. These successive mitoses are characterized by an incomplete cytokinesis, so that daughter cells remain connected through a cytoplasmic bridge.…”

Section: Early Gametogenesis − From Germline Stem Cells To Entry Of Mmentioning

confidence: 99%

“…The interconnected germ cells are packaged as a cyst and surrounded by somatic cells. Following several rounds of mitosis, the cells enter meiosis to become eggs in the ovary or sperms in the testis 28, 29. Interestingly, the number of successive division rounds differs between oogenesis and spermatogenesis in medaka 20, 30.…”

Section: Early Gametogenesis − From Germline Stem Cells To Entry Of Mmentioning

confidence: 99%

Germline stem cells are critical for sexual fate decision of germ cells

Tanaka

2016

BioEssays

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Egg or sperm? The mechanism of sexual fate decision in germ cells has been a long‐standing issue in biology. A recent analysis identified foxl3 as a gene that determines the sexual fate decision of germ cells in the teleost fish, medaka. foxl3/Foxl3 acts in female germline stem cells to repress commitment into male fate (spermatogenesis), indicating that the presence of mitotic germ cells in the female is critical for continuous sexual fate decision of germ cells in medaka gonads. Interestingly, foxl3 is found in most vertebrate genomes except for mammals. This provides the interesting possibility that the sexual fate of germ cells in mammals is determined in a different way compared to foxl3‐possessing vertebrates. Considering the fact that germline stem cells are the cells where foxl3 begins to express and sexual fate decision initiates and mammalian ovary does not have typical germline stem cells, the mechanism in mammals may have been co‐evolved with germline stem cell loss in mammalian ovary.

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Vasa expression is associated with sex differentiation in the Asian yellow pond turtle, Mauremys mutica

et al. 2021

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Vasa, one of the best‐studied germ cell markers plays a critical role in germ cell development and differentiation in animals. Vasa deficiency would lead to male‐specific sterility in most vertebrates, but female sterility in the fly. However, the role of the vasa gene involved in germ cell differentiation is largely elusive. Here, we first characterized the expression profile of vasa products in the Asian yellow pond turtle by quantitative reverse‐transcription polymerase chain reaction and fluorescence immunostaining. The results showed that vasa messenger RNA (mRNA) is initially detected in embryos at stage 16, and then dramatically increased in embryos at stage 19. In particular, like the sex‐related genes, vasa mRNA exhibited differential expression in embryos between the male‐producing temperature (MPT, 25°C) and the female‐producing temperature (FPT, 33°C), whereas there was no difference in methylation levels of vasa promoter detected between FPT and MPT. In contrast, in the adult Asian yellow pond, the level of vasa mRNA was much higher in the testis than ovary. Moreover, the immunostaining on testicular sections and cells showed that Vasa protein was exclusively expressed in germ cells: Weak but detectable in spermatogonia, highest in spermatocytes, moderate and concentrated in chromatid bodies in spermatids and spermatozoa, and bare in somatic cells. The expression profile of Vasa protein is similar in turtle species studied so far but distinct from those in fish species in this study. The findings of this study would provide new insights into our understanding of the conservation and divergence of the vasa gene, even other germ cell genes across phyla.

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Gonadal Development in Fish

Cited by 86 publications

References 57 publications

A Structurally and Functionally Common Unit in Testes and Ovaries of Medaka <b><i>(Oryzias latipes)</i></b>, a Teleost Fish

A Structurally and Functionally Common Unit in Testes and Ovaries of Medaka <b><i>(Oryzias latipes)</i></b>, a Teleost Fish

Germline stem cells are critical for sexual fate decision of germ cells

Vasa expression is associated with sex differentiation in the Asian yellow pond turtle, Mauremys mutica

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