• after 7 months the average weight was identical to that of mice heterozygous only for Sim1^tm1Fan

• paraventricular nucleus and supraoptic nuclei are hypocellular

• the phenotype is identical to that of mice heterozygous only for Sim1^tm1Fan

• at E18.5, the principal mammillary axonal tract appears thin and the mammilothalmic tract is undetectable

• most mammillary body axons are directed towards the midline with some becoming splayed and others forming a bundle that crosses the midline ventrally

• at E18.5, the principal mammillary axonal tract appears less prominent similar to mice homozygous for Sim1^tm1Fan alone

• at E18.5, the principal mammillary axonal tract appears less prominent similar to mice homozygous for Sim1^tm1Fan alone

• at E18.5, the principal mammillary axonal tract and mammilothalmic tract are absent

• on the mammillary body in the location of the principal mammillary axonal tract a group of ectopic axons is seen and at the most posterior level of the mammillary body these axons cross the midline ventrocaudally to the third ventricle

• at E11.5 mammillary body axon bundles are not detectable