Macrophage appeared at stage 14, while myoid cells and thymic APUD cells located in thymic medulla at stage 15 and their numbers slightly increased at stage 16.

• 巨噬细胞以及肌样细胞和胸腺APUD细胞分别形成于胚胎发育14期和15期，随后数量有所增加，分别分布于胸腺皮质和髓质。