INSL3 and cryptorchidism: Numerous studies in pregnant rats have shown that maternal exposure to a variety of environmental endocrine disrupting chemicals (EDCs) leads to a reduction in INSL3 mRNA or protein expression by the fetal Leydig cells (Figure 4) with disruption of the male reproductive phenotype, including cryptorchidism, hypospadias, and reduced anogenital distance (65–67).