Origin of the thymic myoid cells in birds: H. Nakamura, K. Watanabe, C. Ayer-Le Lievre, and N. Le Douarin. Dept. of Anatomy, Hiroshima Univ. Sch. of Med., Kasumi 1-2-3, Minami-ku, Hiroshima 734, Japan, Dept. of Anatomy, Fukui Med. Sch., Fukui, Japan and Institut d'Embryologie du CNRS et du Collège de France, Nogent-sur-Marne, France