Identification of morc (microrchidia), a mutation that results in arrest of spermatogenesis at an early meiotic stage in the mouse

M. L. Watson, A. R. Zinn, N. Inoue, K. D. Hess, J. Cobb, M. A. Handel, R. Halaban, C. C. Duchene, G. M. Albright, R. W. Moreadith

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The microrchidia, or more, autosomal recessive mutation results in the arrest of spermatogenesis early in prophase I of meiosis. The more mutation arose spontaneously during the development of a mouse strain transgenic for a tyrosinase cDNA construct. Morc-/- males are infertile and have grossly reduced testicular mass, whereas -/- females are normal, indicating that the Morc gene acts specifically during male gametogenesis. Immunofluorescence to synaptonemal complex antigens demonstrated that -/- male germ cells enter meiosis but fail to progress beyond zygotene or leptotene stage. An apoptosis assay revealed massive numbers of cells undergoing apoptosis in testes of - /- mice. No other abnormal phenotype was observed in mutant animals, with the exception of eye pigmentation caused by transgene expression in the retina. Spermatogenesis is normal in +/- males, despite significant transgene expression in germ cells. Genomic analysis of -/- animals indicates the presence of a deletion adjacent to the transgene. Identification of the gene inactivated by the transgene insertion may define a novel biochemical pathway involved in mammalian germ cell development and meiosis.

Original languageEnglish (US)
Pages (from-to)14361-14366
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number24
Publication statusPublished - Nov 24 1998


ASJC Scopus subject areas

  • Genetics
  • General

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