This spontaneous mutation causes bends and kinks in the tail and reduced spermiogenesis. Histology also shows segmental tubular degeneration and atrophy in the testes with germ cell depletion. The underlying molecular lesion has not been identified. Because of the male infertility, sperm cryopreservation was done from heterozygous males, thereby requiring a progeny test to identify homozygotes after cryo-recovery.Read More +
Mice homozygous for this recessive mutation may have one or more tail kinks or bend in the tail, but there is variable expressivity and possibly incomplete penetrance. Some tail kinks are only identifiable by palpation. Heterozygous intercrosses generated approximately 11% phenotypic mutants and homozygote x heterozygote crosses also generated approximately 11% phenotypic mutants. Histological assessment of two 28-week-old mutants found segmental tubular degeneration and atrophy, reduced spermiogenesis, evidence of germ cell depletion, and possible degeneration of cartilage in the femoral growth plate and underside of the patella in one mouse. One attempt at in vitro fertilization of BALB/cByJ oocytes with sperm from a homozygote failed.
The variable tail abnormalities (vtab) mutation arose spontaneously in the CByJ.A-Ttc7fsn/J strain at The Jackson Laboratory. The flaky skin mutation was bred out of this mutant subline and this strain was maintained by breeding heterozygous vtab males with either homozygous or heterozygous females. Sperm from homozygous males failed to fertilize BALB/cByJ oocytes in in vitro fertilization, so sperm was cryopreserved from heterozygous males.
Due to the diminished spermiogenesis male homozygotes should not be used for breeding. Fewer mutants are generated, even from heterozgyous intercrosses, than the expected Mendelian ratios.
When using the variable tail abnormalities mouse strain in a publication, please cite the originating article(s) and include JAX stock #017683 in your Materials and Methods section.