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The fetal circulation is composed of the placenta, umbilical blood vessels encapsulated by the umbilical cord, heart and systemic blood vessels. A major difference between the fetal circulation and postnatal circulation is that the lungs are not used during the fetal stage resulting in the presence of shunts to move oxygenated blood and ...
Human embryo at approximately 30 days, showing development of various structures including the yolk sac.From Gray's anatomy. Vasculogenesis is the formation of early vasculature, which is laid down by genetic factors. [7]
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 catheter may be inserted into one of the umbilical arteries of critically ill babies for drawing blood for testing. [6] This is a common procedure in neonatal intensive care, and can often be performed until 2 weeks after birth (when the arteries start to decay too much). [7]
The unpaired umbilical vein carries oxygen and nutrient rich blood derived from fetal-maternal blood exchange at the chorionic villi.More than two-thirds of fetal hepatic circulation is via the main portal vein, while the remainder is shunted from the left portal vein via the ductus venosus to the inferior vena cava, eventually being delivered to the fetal right atrium.
A study of 32 normal pregnancies showed that fetal heart motion was visible at a mean human chorionic gonadotropin (hCG) level of 10,000 UI/L (range 8650–12,200). [19] Obstetric ultrasonography can also use Doppler technique on key vessels such as the umbilical artery to detect abnormal flow. Doppler fetal monitor
Step 4: Outflow tract septation. The truncus arteriosus and the adjacent bulbus cordis partition by means of cells from the neural crest. [1]
In either case, angiogenesis is a necessary and required step for transition from a small harmless cluster of cells, often said to be about the size of the metal ball at the end of a ball-point pen, to a large tumor. Angiogenesis is also required for the spread of a tumor, or metastasis. [9]