Objective to study the blood drainage system of Langerhans islets in the primates with special reference to the functional and clinical significance of pancreatic portal circulation.

That found in medullary carcinoma of the thyroid appears to have calcitonin or precalcitonin as its precursor, while the amyloid which occurs in the islets of Langerhans may be derived from insulin .

Scattered among the enzyme-producing cells are the islets of Langerhans, which secrete insulin and glucagon directly into the bloodstream.