Circadian rhythms of the endocrine pancreas. A quantitative biochemical and immumocytochemical study.

Cellular hormone levels of insulin and glucagon in the endocrine pancreas of the rat have been observed and quantified over the 24-hours period, at 3-hourly intervals, by T.V. image conversion analysis on immunocytochemical preparations. Parallel estimations of blood sugar were carried out. Glucagon levels were at their lowest when the blood sugar levels were at their highest. Quantitative cytochemistry is regarded as a valuable tool for the investigation of changes in intracellular hormone levels under physiological and pathological conditions.