Ultrastructural studies of tw32/tw32 mouse embryos

Area of Science:

• Developmental Biology
• Genetics
• Mouse Embryology

Background:

• The T locus plays a crucial role in mouse embryonic development.
• Recessive alleles at the T locus can cause embryonic lethality.
• Previous studies suggested potential allelism between tw32 and t12.

Purpose of the Study:

• To characterize the lethal phenotype of homozygous tw32/tw32 mouse embryos.
• To determine the allelic relationship between tw32 and t12.

Main Methods:

• Analysis of homozygous tw32/tw32 mouse embryos from specific crosses.
• Microscopic examination of embryonic morphology and cellular characteristics.
• Phenotypic comparison of mutant embryos with wild-type littermates.

Main Results:

• Homozygous tw32/tw32 embryos exhibit a lethal period from the 8-12 cell stage to the late morula stage.
• Key features include excessive cytoplasmic and nuclear lipid droplets, mitochondrial abnormalities, and binucleated cells.
• These distinct features allow for identification of presumed homozygotes prior to the lethal period.
• The tw32 allele is shown to be non-complementary with the t12 allele.

Conclusions:

• The tw32 mutation causes severe developmental defects leading to embryonic lethality in mice.
• The observed phenotype distinguishes homozygous tw32/tw32 embryos.
• The tw32 and t12 alleles are confirmed as separate, recessive alleles at the T locus.