CULTIVATION IN VITRO OF THE THYROID GLAND

A THREE MONTHS OLD STRAIN OF EPITHELIUM

1. A strain of pure epithelial cells was obtained from the part of the iris which adheres to the extirpated lens. 2. The optimum condition under which epithelial cells grow in vitro is on the free surface of the plasma clot under a film of embryonic tissue juice. 3. The epithelial cells did not dedifferentiate. Although the strain is 3 months old, they grow as a pavement membrane and have kept their epithelial characteristics.

A PURE STRAIN OF THYROID CELLS AND ITS CHARACTERISTICS

1. A pure strain of thyroid epithelium was isolated and maintained in active condition for 7 months. At the end of the experiment, the rate of cell multiplication was as great as at its beginning. 2. The thyroid cells grew at the surface of the coagulum as pavement epithelium, and within the coagulum as a glandular structure. 3. The cells did not dedifferentiate, and the lumen of the acini in cultures from a strain over 4 months old contained colloid secretion similar morphologically to that from a freshly extirpated thyroid gland.