Distribution of Calcitonin-Containing Cells in the Normal Adult Human Thyroid Gland: A Correlation of Morphology with Peptide Content

The distribution of C-cells in the adult human thyroid gland was mapped by a combination of immunoperoxidase localization, biological assay and radioimmunoassay. C-cells are concentrated along the central axis of the lateral lobes in their middle thirds and are predominantly distributed individually in parafollicular and intrafollicular locations. The relative numbers of C-cells observed per unit area of thyroid tissue correlated strongly with the calcitonin content of immediately adjacent tissue sections. The total ranges determined were from fewer than 2 immunoperoxidase-staining cells per low power field (calcitonin content < 0.50 to 5.0 MRC mU/g fresh weight) in the extremes of the upper and lower poles to 4–10 stained cells per low power field (10 to 160 MRC mU/g) in the midportions of the lateral lobes.