The baby will return to this habit long after birth, when weaned, to relive the sensation of happy, satisfied need. The infant's sex is determined when the sperm fertilizes the ovum, but no external difference is obvious. The external genital organs develop between the second and third month. The hands, close-up, appear perfectly formed. Because they are still translucent the cartilage is visible.
Fetal circulation is a special type.
Oxygenation of the blood is accomplished through the placenta rather than through the lungs as in adults. The auricles and ventricles of the heart are formed but interconnect by openings. If these openings persist too long they constitute a recognized malformation that has been successfully cured by surgery. All rights reserved .