Development of the endocrine system of gestation, somatotroph cells begin to develop with cytoplasmic expression of human growth hormone. Once a fetus reaches 12 weeks of development, the thyrotrophs begin expression of Beta subunits for TSH, while gonadotrophs being to express beta-subunits for LH and FSH. Male fetuses predominately produced LH-expressing gonadotrophs, while female fetuses produce an equal expression of LH and FSH expressing gonadotrophs. At 24 weeks of gestation, prolactin-expressing lactotrophs begin to emerge. Development of the endocrine system The fetal endocrine system is one of the first systems to develop during prenatal development. The fetal adrenal cortex can be identified within four weeks
Endocrine disruptor BDE-47, affects the reproductive system and thyroid gland of female rats in doses of the order of those to which humans are exposed. Low concentrations of endocrine disruptors can also have synergistic effects in amphibians, but it is not clear that this is an effect mediated through the endocrine system. Critics have argued that data suggest that the amounts of chemicals in the environment are too low to cause an effect. A consensus statement by the Learning and Developmental Disabilities Initiative argued that "The very low-dose effects of endocrine disruptors cannot be predicted from high-dose studies, which contradicts the standard