Arrest of spermatogenesis and defective breast development in mice lacking A-myb

Nature. 1997 Apr 17;386(6626):713-7. doi: 10.1038/386713a0.


The Myb gene family currently consists of three members, named A-, B- and c-myb. These genes encode nuclear proteins that bind DNA in a sequence-specific manner and function as regulators of transcription. In adult male mice, A-myb is expressed predominantly in male germ cells. In female mice, A-myb is expressed in breast ductal epithelium, mainly during pregnancy-induced ductal branching and alveolar development. We report here that mice homozygous for a germline mutation in A-myb develop to term but show defects in growth after birth and male infertility due to a block in spermatogenesis. Morphological examination of the testes of A-myb-/- males revealed that the germ cells enter meiotic prophase and arrest at pachytene. In adult homozygous null A-myb female mice, the breast epithelial compartment showed underdevelopment of breast tissue following pregnancy and the female mice were unable to nurse their newborn pups. These results demonstrate that A-myb plays a critical role in spermatogenesis and mammary gland development.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Female
  • Gene Expression
  • Gene Targeting
  • Germ-Line Mutation
  • Infertility, Male / genetics
  • Male
  • Mammary Glands, Animal / anatomy & histology
  • Mammary Glands, Animal / embryology
  • Mammary Glands, Animal / growth & development
  • Mammary Glands, Animal / physiology*
  • Meiosis
  • Mice
  • Molecular Sequence Data
  • Pregnancy
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / physiology*
  • Proto-Oncogene Proteins c-myb
  • Spermatogenesis / genetics
  • Spermatogenesis / physiology*
  • Stem Cells
  • Testis / anatomy & histology
  • Testis / embryology
  • Testis / growth & development
  • Testis / physiology*
  • Trans-Activators / genetics
  • Trans-Activators / physiology*


  • Mybl1 protein, mouse
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-myb
  • Trans-Activators

Associated data

  • GENBANK/U90890