γ-ray exposure accelerates spermatogenesis of medaka fish, Oryzias latipes

Yoshikazu Kuwahara, Atsuko Shimada, Hiroshi Mitani, Akihiro Shima

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

To examine the spermatogenesis (and spermiogenesis) cell population kinetics after γ-irradiation, the frequency and fate of BrdU-labeled pre-meiotic spermatogenic cells (spermatogonia and pre-leptotene spermatocytes) and spermatogonial stem cells (SSCs) of the medaka fish (Oryzias latipes) were examined immunohistochemically and by BrdU-labeling. After 4.75 Gy of γ-irradiation, a statistically significant decrease in the frequency of BrdU-labeled cells was detected in the SSCs, but not in pre-meiotic spermatogenic cells. The time necessary for differentiation of surviving pre-meiotic spermatogenic cells without delay of germ cell development was shortened. More than 90% of surviving pre-meiotic spermatogenic cells differentiated into haploid cells within 5 days after irradiation, followed by a temporal spermatozoa exhaust in the testis. Next, spermatogenesis began in the surviving SSCs. However, the outcome was abnormal spermatozoa, indicating that accelerated maturation process led to morphological abnormalities. Moreover, 35% of the morphologically normal spermatozoa were dead at day 6. Based on these results, we suggest a reset system; after irradiation most surviving spermatogenic cells, except for the SSCs, are prematurely eliminated from the testis by spermatogenesis (and spermiogenesis) acceleration, and subsequent spermatogenesis begins with the surviving SSCs, a possible safeguard against male germ cell mutagenesis.

Original languageEnglish
Pages (from-to)204-211
Number of pages8
JournalMolecular Reproduction and Development
Volume65
Issue number2
DOIs
Publication statusPublished - 2003 Jun 1

Keywords

  • BrdU
  • Cell cycle arrest
  • Medaka fish
  • Radiation
  • Spermatogenesis
  • Spermatogonial stem cells

ASJC Scopus subject areas

  • Genetics
  • Developmental Biology
  • Cell Biology

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