Development of the endocrine system alpha cells. The insulin concentration within the fetal pancreas is 3.6 pmol/g at seven to ten weeks, which rises to 30 pmol/g at 16–25 weeks of gestation. Near term, the insulin concentration increases to 93 pmol/g. The endocrine cells have dispersed throughout the body within 10 weeks. At 31 weeks of development, the islets of Langerhans have differentiated. While the fetal pancreas has functional beta cells by 14 to 24 weeks of gestation, the amount of insulin that is released into the bloodstream is relatively low. In a study of pregnant women carrying fetuses in the mid-gestation and near term
Paul Langerhans Paul Langerhans Paul Langerhans (25 July 1847 – 20 July 1888) was a German pathologist, physiologist and biologist, credited with the discovery of the cells that secrete insulin, named after him as the islets of Langerhans. Langerhans was born in Berlin on 25 July 1847, the son of a physician. He later entered the renowned Graues Kloster in the same city. Due to his outstanding performance he was exempted from the final oral examinations. He began his medical studies at the University of Jena and completed them in Berlin. In February 1869, he presented a thesis entitled “Contributions to the