Blood sugar regulation cells in the pancreatic islets are among the most well understood and important. If the blood glucose level falls to dangerous levels (as during very heavy exercise or lack of food for extended periods), the alpha cells of the pancreas release glucagon, a hormone whose effects on liver cells act to increase blood glucose levels. They convert glycogen into glucose (this process is called glycogenolysis). The glucose is released into the bloodstream, increasing blood sugar. Hypoglycemia, the state of having low blood sugar, is treated by restoring the blood glucose level to normal by the ingestion or administration of dextrose
Corpuscle of Stannius composed of several columnar cells, which contain secretory granules and are, thus, secretory in function. Each Secretory granule is spherical in shape and measures 0.5 to 1 μm in diameter. Their possible endocrine nature, i.e. producing hormone, was suspected from the complete anatomical description, and it was believed to be responsible for regulating calcium level in the blood. The hormone was identified as stanniocalcin. Bony fishes obtain calcium directly from their aquatic surrounding (unlike other vertebrates which acquire from diet), so that they require separate endocrine organ. The corpuscles of Stannius are the sites of production of the hormone called