マウス奇形耳小骨の病態に関する病理形態学的研究

Pregnant ddN mice were injected with 15,000 I.U. of water miscible vitamin A intraperitoneally on day 8 of pregnancy. Fetuses were removed surgically on day 18. Twenty of them were selected randomly to be sectioned horizontally and stained with hematoxylin and eosin solution for histological observation of the malformed ossicles. The malleus, incus and stapes were suggested by the observations to have developed directly from branchial arch cartilage: the former two from Meckel's cartilage and the latter from Reichert's cartilage. That the stapes was isolated might lend support to the theory of dual origin of the footplate. The above results were discussed with embryological and bibliographical considerations.