Figure 4.

Two models for thyroid regeneration in mice. Model I may be operable when the damage to the thyroid is modest such as when a small portion of thyroid (tissues below the line) is removed. This model may take 2–4 weeks to start producing functionally matured thyrocytes, and may involve immature cells in SCN. SCA1-expressing cells and SCN-like immature cells are shown in red and in pale color, respectively. Ciliated cells are also shown within the immature cells. Model II may become functional when the thyroid damage is massive such as semi-total partial thyroidectomy (a whole lobe and the other lobe below the line as indicated are removed). In this case, follicular cells and C cells are reset to become clear immature cells (shown in light yellow) to start the maturation process again. This model may take 1–2 weeks to start producing functionally mature thyrocytes. Both models can operate simultaneously. PTx, partial thyroidectomy.