Reproductive development and function are a complex process requiring the coordinate interactions of multiple extragonadal and intragonadal factors. Peptide hormones from the hypothalamus (eg, gonadotropin releasing hormone) and the pituitary (eg, follicle stimulating hormone, luteinizing hormone, oxytocin) as well as growth factors and steroids from the gonads (eg, inhibins, growth differentiation factor-9, progesterone, estradiol, testosterone) play key functions in regulating specific aspects of reproduction. Our laboratory used spontaneous mutant mice and transgenic mouse models to address the essential roles of some of these factors in the propagation of the mammalian species. This review summarizes some of our initial studies to understand this process.