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K. Sawada
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K. Sakamaki
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Y. Nishimune
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Summary. The effect of the mutation for white belly spot controlled by the dominant gene W on spermatogenesis in mice was examined by experimental cryptorchidism and its surgical reversal. The course of spermatogenesis from spermatogonia to spermatid was normal in intact testes of W/+ mice. In cryptorchid testes, there was no difference in the number and activity of Type A spermatogonia between the testes of W/+ and +/+ mice, in mitotic and labelling indices. Although surgical reversal of the cryptorchid testis resulted in regenerative differentiation of germ cells in both genotypes, the recovery of cell differentiation in the W/+ testis was slower than in the +/+ testis. There were fewer germ cells, such as intermediate–Type B spermatogonia or more advanced ones, in W/+ testes. On Day 17 after surgical reversal, cell associations in W/+ testes were abnormal and the numbers of intermediate–Type B spermatogonia, spermatocytes and spermatids were approximately ∼70, 50 and 15%, respectively, of those in +/+ testes. These results indicate that the W gene affects spermatogenic cell differentiation in adult mice.

Keywords: W mutation; spermatogenesis; cryptorchidism; orchidopexy; mouse

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Y. Tajima
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K. Sawada
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T. Morimoto
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Y. Nishimune
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Testicular cells composed mostly of germ cells and immature Sertoli cells from neonatal mice 2 and 5 days old were cultured to investigate germ-cell proliferation mediated by the c-kit receptor. The addition of antibody to block the interaction of the c-kit receptor with its ligand inhibited the proliferation of cultured spermatogonia from 5-day-old mice in a dose-dependent manner, but not from that of 2-day-old mice. The addition of anti-c-kit ACK2 monoclonal antibody also inhibited the proliferation of spermatogonia from 5-day-old mutant Sld/Sld mice but not of 5-day-old mutant Wo/Wo mice. The results indicate that c-kit-positive type A spermatogonia in the testes of 5-day-old mice require steel factor (kit ligand) for their proliferation, whereas self-renewal and differentiation of c-kit-negative primitive type A spermatogonia in the testes of 2-day-old mice do not.

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