Mark Sornson performed this study as a graduate student at UCSD in the Rosenfeld lab.

About the Image: Shown is a normal wild-type mouse and a mouse with a genetic form of dwarfism (df/ef).  A novel positional cloning was used to define the responsible gene as one encoding a novel homeodomain protein, referred to as Prop-1, which exhibits pituitary-specific expression. 

The basis of the Prop-1 mutation is a failure of asymmetric division of perilumenal cells of the anterior pituitary gland, leading to a loss of Pit-1 expression and loss of three cell types—somatotropes, producing growth hormones; lactotropes, producing prolactin and thyrotropes, producing thyroid stimulator hormone. 

These data are presented in Sorenson, M.W. et al. Pituitary lineage determination by the Prop-1 homeodomain factor defective in Ames dwarfism. Nature (Article) 384:327–333 (1996).  [Abstract]