MICROANATOMY

Detailed explanation-1: -Protein hormones, made in large amounts in neuroendocrine cells, are stored in large dense-core vesicles packed with protein, commonly known as secretory granules.

Detailed explanation-2: -Secretory granules are specialized intracellular organelles that serve as a storage pool for selected secretory products.

Detailed explanation-3: -The secretory pathway occurs in a vectorial manner and begins with uptake of amino acids that are used by the rough endoplasmic reticulum to produce newly synthesized proteins. These new proteins are transported to the Golgi complex for further processing and sorting.

Detailed explanation-4: -Insulin is synthesized as proinsulin in the endoplasmic reticulum (ER) and transported to the Golgi apparatus. In the trans-Golgi network (TGN), insulin becomes hexamer, and then packaged into secretory granules (Figure 1). In secretory granules, proinsulin is processed to form mature insulin and C-peptide.