Presumptive teratological consequences of the soluble, fetal and dam-foreign antigens (sFF-Ag) being neutralized by their specific IgY. Both embryos were 53-h old. The one on the left (the control) exhibited normal development: with twenty-two pairs of somites, optic cup, lens and choroids fissure, 1st, and 2nd pharyngeal pouch and the arches 1 and 2, otic vesicle, normal looping of the heart (atrium, ventricle and troncus arteriosus), etc. On the right, the embryo shows a more reduced body size, and all the abovementioned anatomical structures are much less noticeable here. What is most noticeable is the malformed development of the brain, pharynx and heart.