Slide DMS142 [Pancreas, human, H&E]. The endocrine cells of the pancreas are aggregated into small, spherical clusters known as islets (of Langerhans) which are scattered among the exocrine acini and ducts. The cells of the islets are arranged into compact anastamosing cords that are extensively vascularized by fenestrated capillaries, as would be expected of endocrine glands in general. In contrast with the exocrine pancreas, there are no ducts associated with the islets. Each islet cell is closely apposed to a capillary so that the hormones are released directly into pericapillary space. Using this relatively thick but typical H&E section test your ability to recognize islets amongst the exocrine components of the pancreas. The embryonic origin of islet tissue is still in question.