Figure 1722

Photomicrograph of the pancreas. This H&E-stained specimen shows a number of pancreatic lobules separated by connective tissue septa that are continuous with the thin surrounding capsule of the gland. The pancreatic lobules consist largely of the exocrine acini and their intralobular duct system. Most of the lobules exhibit small, round, lighter-staining profiles, which are the islets of Langerhans (arrows). Adjacent to the lobules, at the lower left, is a large Interlobular duct that serves the exocrine pancreas. x25.

procedure. TEM allows identification of the principal cell types by the size and density of their secretory granules.

Islet cells, other than B cells, are counterparts of the enteroendocrine cells of the gastrointestinal mucosa

In addition to the three principal islet cells, three minor islet cell types have also been identified by using a combination of the TEM and immunocytochemistry (Table 17.3). Each cell type can be correlated with a specific hormone, and each has a specific location in the islet.

B cells constitute about 70% of the total islet cells in humans and are generally located in its central portion. They secrete insulin (see Table 17.2). B cells contain numerous secretory granules about 300 nm in diameter with a dense polyhedral core and a pale matrix. The polyhedral core is believed to be crystallized insulin.

A cells constitute about 15 to 20% of the human islet population and are generally located peripherally in the

Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

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