The Xenopus tropicalis Model for Studies of Developmental and Reproductive Toxicity

The reproductive cycle encompasses processes such as sex organ differentiation and development in the early life stages and maturation of the gametes in the adult organism. During the early life stages, critical developmental programming of the endocrine and reproductive systems occurs, and exposure to chemicals during these critical developmental windows can result in impaired reproductive function later in life. It is therefore important to evaluate long-term consequences of early life stage exposure to endocrine-disrupting chemicals. The African clawed frog Xenopus tropicalis has several characteristics that facilitate studies of developmental and reproductive toxicity. Here I present a X. tropicalis life cycle test protocol including study design, exposure regimes, and endpoints for chemical disruption of sex differentiation, gonadal and Müllerian duct development, the thyroxin-regulated metamorphosis, estrogen synthesis (activity of the CYP19 aromatase enzyme), spermatogenesis, oogenesis, puberty and fertility.