Distribution of C cells in monkey thyroid glands as studied by the immunoperoxidase method using anti-calcitonin and...

The distribution of C cells in the thyroid glands of eight young adult monkeys (4 Macaca fuscata and 4 Macaca irus) was investigated by complete serial sections utilizing the immunoperoxidase method with anti-human calcitonin and anti-dog C-thyroglobulin antisera. The secretory granules of monkey C cells were strongly immunoreactive to both antisera. A markedly uneven distribution of C cells was found. The C cells were distributed in a small area restricted to the dorsomedial portion of the lobe along the longitudinal axis below the parathyroid IV, while the remaining larger portions were devoid of C cells. In the areas where the C cells were concentrated, the cells were scattered, surrounding a large portion or even the whole of the epithelium lining follicles and often forming multiple clusters among the follicles. In these places the C cells exceeded the number of follicular cells.