The improvement in reproductive parameters in Prop1df/df mice was closely associated with GH replacement, since it is known that GH stimulates various aspects of gonadal function in hypophysectomized animals and in animals with hypopituitarism due to genetic mutations through its effect on the release of GnRH by the hypothalamus (10,11) and gonadotropins by the pituitary gland (12,13). This evidence concerns the gene GNRH1 and hypopituitarism.