A Human Embryo of Carnegie Stage 12

Abstract

A human embryo obtained from a salpinx removed for the treatment of tubal gestation was serially sectioned and observed. On gross examination, the embryo showed three prominent pharyngeal arches, but not the cervical sinus. The upper arm bud had just begun to appear with a slight elevation in the skin ectoderm. Both the anterior and posterior neuropores had already been closed. The heart was at the cardiac loop stage. The respiratory diverticulum, the dorsal pancreas and the beginning of the omental bursa had appeared. In the pharyngeal region, the adenohypophyseal pocket and the thyroid anlage were observed. The optic evagination showed no regional differentiation yet. From the above findings, we concluded that this embryo belonged to Carnegie stage 12.