Human Parathyroid (H&E) [#116]: Is mainly composed of two cell populations - the chief cells and the oxyphil cells. The chief cells are the most common cell type and are responsible for secretion of parathyroid hormone. They are relatively small and are characterized by a large vesicular nucleus and a generally light staining cytoplasm. The oxyphil cells are scarce and may occur singly or in large clusters. They are relatively larger cells with deeply eosinophilic cytoplasm. Adipose (fat) cells are often seen in the connective tissue stroma.