Mice homozygous for the Tlx1tm1Sjk targeted mutation lack a spleen; however, all other internal organs are normal. Characteristics include: dominant hemimelia (spontaneous mutation in the mouse), asplenia and many other defects including polydactyly or oligodactyly of the hindlimbs, tibial hemimelia, and sometimes reduction of the femur and pubic element of the pelvic girdle. Pharyngeal and mastication muscles derived from the branchial arches are present and anatomically normal homozygotes have normal cranial ganglia morphology and position and normal cranial motor nuclei function. There are normal numbers of RBCs but increased numbers of WBCs, including neutrophils and lymphocytes. The B-cell and T-cell profile is normal in the thymus, lymph nodes and peripheral blood. Many erythrocytes have nuclear fragments (Howell-Jolly bodies).
In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. This is the case for the strain above. It should be noted that the phenotype could vary from that originally described. We will modify the strain description if necessary as published results become available.
