New Strain Characteristic Documented for Inbred Strain A/HeJ (Stock Number 000645)

JAX® NOTES Issue 500, Winter 2006

In 1993, an A/HeJ inbred mouse with abnormal external genitalia was obtained from the The Jackson Laboratory Production Colonies. Further inspection of nonproductive A/HeJ male mice indicates that 4% are hermaphrodites characterized by mixed female and male external genitalia and ovaries and/or ovotestes. An additional 17% of nonproductive males have abnormally small testes containing no sperm. This observation is reminiscent of the hermaphrodism found in BALB/cWt mice. It is caused by non-disjunction of the Y chromosome during early embryonic development (Eicher et al. 1980). In BALB/Wt mice, mosaicism for populations of X0 and XY, or X0, XY, and XYY cells results in individuals with both ovarian and testicular tissue. The more ovarian tissue present, the more likely the external genitalia appear abnormal.

C57BL/6J females mated to A/HeJ males produce some XY F1 fetuses with gonads containing both ovarian and testicular tissue (ovotestes) (Bean et al. 2001). In contrast, the presence of the BALB/cWt Y chromosome does not modify male reproductive development in (C57BL/6J x BALB/cWt) F1 XY mice (Beamer et al. 1978). We are investigating the cause of hermaphroditism in the A/HeJ inbred strain with Dr. Patricia A. Hunt and graduate student Jodi Jackson of the School of Molecular Biosciences, Washington State University Pullman, WA.
(Note: this abnormality is not a characteristic of the A/J (000646) inbred strain.)

References

Eicher EM, Beamer WG, Washburn LL, Whitten WK. A cytogenetic investigation of inherited true hermaphroditism in BALB/cWt mice. 1980. Cytogenet Cell Genet 28:104-15.

Bean CJ, Hunt PA, Millie EA, Hassold TJ. 2001. Analysis of a malsegregating mouse Y chromosome: evidence that the earliest cleavage divisions of the mammalian embryo are non-disjunction-prone. Hum Mol Genet 10:963-72.

Beamer WG, Whitten WK, Eicher EM. 1978. Spontaneous sex mosaicism in BALB/cWt mice. In: Russell LD, editor. Genetic Mosaics and Chimeras in Mammals. Plenum Publishing Corporation; 485 p.

-Linda Washburn, M.S.