Situs inversus in homozygous mice without immotile cilia.

Mice homozygous for the mutation situs inversus, iv, are characterized by situs inversus in 50 percent of the individuals. We have investigated the ultrastructure and motility of tracheal cilia and sperm tails in homozygous individuals with and without situs inversus. We found no abnormalities of ciliary structure. Therefore, ciliary immotility is not an essential correlate of situs inversus.