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It is the fetal heart and not the mother's heart that builds up the fetal blood pressure to drive its blood through the fetal circulation. Intracardiac pressure remains identical between the right and left ventricles of the human fetus.
The heart is the first functional organ in vertebrate embryos. The tubular heart quickly differentiates into the truncus arteriosus, bulbus cordis, primitive ventricle, primitive atrium, and the sinus venosus. The truncus arteriosus splits into the ascending aorta and the pulmonary trunk. The bulbus cordis forms part of the ventricles.
Human embryonic development covers the first eight weeks of development, which have 23 stages, called Carnegie stages. At the beginning of the ninth week, the embryo is termed a fetus (spelled "foetus" in British English). In comparison to the embryo, the fetus has more recognizable external features and a more complete set of developing organs.
The truncus arteriosus and bulbus cordis are divided by the aorticopulmonary septum.The truncus arteriosus gives rise to the ascending aorta and the pulmonary trunk.The caudal end of the bulbus cordis gives rise to the smooth parts (outflow tract) of the left and right ventricles (aortic vestibule & conus arteriosus respectively). [2]
A fetus receives oxygen not from its lungs, but from the mother's oxygen-rich blood via the placenta. Oxygenated blood from the placenta travels through the umbilical cord to the right atrium of the fetal heart. As the fetal lungs are non-functional at this time, the blood bypasses them through two cardiac shunts.
The tubular heart or primitive heart tube is the earliest stage of heart development. [1] The heart is the first organ to develop during human embryonic development. [2]From the inflow to the outflow, the tubular heart consists of sinus venosus, primitive atrium, the primitive ventricle, the bulbus cordis, and truncus arteriosus. [3]
A newly developing human is typically referred to as an embryo until the ninth week after conception, when it is then referred to as a fetus. In other multicellular organisms, the word "embryo" can be used more broadly to any early developmental or life cycle stage prior to birth or hatching .
A portion remains open as a branch of the anterior division of the internal iliac artery. The umbilical artery is found in the pelvis, and gives rise to the superior vesical arteries, which in males usually supplies the artery to the ductus deferens. Alternately, the latter artery can be supplied by the inferior vesical artery in some individuals.