A method of enhancing the production of gametes in a transgenic non-human animal is carried out by: (a) providing a transgenic non-human animal comprising cells that contain: (i) a response element; (ii) a nucleic acid encoding FSH.beta. operatively associated with the response element; (iii) an FSH.beta. promoter; (iv) an FSH.beta. locus control region operatively associated with the FSH.beta. promoter; and (v) a nucleic acid encoding a ligand-controllable receptor operatively associated with the FSH.beta. promoter, wherein the receptor binds to the response element in the presence of the ligand when expressed in a host cell; and (b) administering the ligand to the animal in an amount effective to (i) stimulate the production of FSH.beta. in the animal above that found in a corresponding untransformed type animal; and (ii) stimulate the production of gametes in the animal to a level greater than that found in the corresponding untransformed animal.