These cells can be found in clusters in the center of the section and at the periphery. Oxyphil cells appear at the onset of puberty, but have no known function. With nuclear medicine scans, they selectively take up the Technetium-sestamibi complex radiotracer dye to allow delineation of glandular anatomy. Oxyphil cells have been shown to express parathyroid-relevant genes found in the chief cells and have the potential to produce additional autocrine/paracrine factors, such as Parathyroid hormone-related protein (PTHrP) and calcitriol. More work needs to be done to fully understand the functions of these cells and their secretions.