Measurement of the weight, i.e., the heaviness or the force with which an object is drawn toward the earth by gravity, of a single pancreatic islet or of the total of all of the islets in the entire pancreas or in a specified part thereof. The pancreas is the elongated, racemose gland containing both endocrine and exocrine elements which secretes hormones such as insulin and glucagon internally and digestive enzymes externally. A pancreatic islet is a small encapsulated region of the pancreas containing endocrine (i.e., hormone-producing) cells.