Abstract
(1) The enamel knot appears as an epithelial cell mass already in the late bud-shaped stage and projected into the dental papilla in the cap-shaped stage. With the advance of development it is replaced by the enamel cord, which is not continuous with the external enamel _ epithelium until the bell-shaped stage. The beginning of amelogenesis is simultaneous with the lost of enamel cord.
(2) The greater the enamel knot becomes, the more compact becomes the mesodermal cells adjacent to it. With the disappearance of the enamel knot the mesoderm condensation vanishes as well.
(3) Mitoses exist only in the peripheral portion of the enamel knot, being reduced in number after the cap-shaped stage. In the enamel cord mitoses are entirely absent.
(4) In the central part of the e namel cord the cells are arranged concentrically, the nucleus slightly swollen, probably a regressive change.
