STEVE GSCHMEISSNER / SCIENCE PHOTO LIBRARY STEVE GSCHMEISSNER / SCIENCE PHOTO LIBRARY
Thyroid gland. Coloured scanning electron micrograph (SEM) of a section through a healthy human thyroid gland. The large follicles (top left & lower right), are lined by cuboidal secretory epithelial cells (red), which are secreting the thyroid hormones T3 (triiodothyronine) and T4 (thyroxine). Layers of epithelial cells (green) surround the follicles. The thyroid follicles are filled with a liquid called thyroglobulin or thyroid colloid, which is a storage form of the thyroid hormones. When inactive, the follicles are distended and the secretory cells flattened. The thyroid, an endocrine gland in the neck, regulates energy levels. Magnification unknown.
Model release not required. Property release not required.