Electron microscopy of the endocrine pancreas of cattle (Bos taurus L.).

The electron-microscopic structure of the islets of Langerhans in cattle is studied. Four cell types are described: A, B, C and D, differing mainly in the structure of specific granules. In the A cells half-moon- or ring-shaped mitochondria are observed. Two modes of islet cell secretion are observed: by means of 'active-releasing sector's and emiocytosis.