Organ culture techniques were applied to sugar maple seeds and seed parts in an attempt to locate the site of dormancy regulation. The study material included the complete embryo with the seedcoat (testa) intact, with the seedcoat removed, and with the seedcoat and cotyledons removed. Results of this study suggest that a number of factors participate in the regulation of seed dormancy, and both the seedcoats and cotyledons are involved. This study also suggests that the stratification process affects seed parts other than the embryonic axis. Forest Sci. 24:43-49.