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γ‐Ray exposure accelerates spermatogenesis of medaka fish, Oryzias latipes
Author(s) -
Kuwahara Yoshikazu,
Shimada Atsuko,
Mitani Hiroshi,
Shima Akihiro
Publication year - 2003
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.10261
Subject(s) - spermatogenesis , oryzias , biology , spermiogenesis , meiosis , andrology , gametogenesis , germ cell , population , microbiology and biotechnology , sperm , genetics , endocrinology , embryo , gene , embryogenesis , medicine , demography , sociology
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. Mol. Reprod. Dev. 65: 204–211, 2003. © 2003 Wiley‐Liss, Inc.