ABSTRACT
Development of the mammalian gonad is an active process in both sexes that requires precise timing and coordination of diverse signaling mechanisms.1
Although the details are not completely understood, understanding of this process has surged in recent years with routine availability of transgenic mouse models and sophisticated techniques for studying gene expression. Failure of the normal program due to delayed and/or insufficient expression of gene products may cause profound, long-term deficiencies in testicular function. It has been known for more than a decade that the sex-determining region on the Y chromosome (SRY) is the switch that triggers testis determination.2 Subsequent work has identified many additional genes that participate in gonadal, testicular and/or ovarian development, the complex mechanisms involved, and the importance of cell-cell interactions in the development of cell types.3,4 Although some species differences are apparent, knowledge of the basic mechanisms of development will aid in understanding the etiology and pathology of testicular and sexual differentiation disorders in children, such as intersex and other disorders of testicular development and descent.
