| At 6 weeks the embryo is about 5cm long and this junior space man floats in his fluid filled capsule- the amnion. This back view shows the neural tube becoming the spinal cord- outlined by 2 thin red vertebral arteries. Leg and arm buds are still growing. The embryo is nourished by the placenta, the spongy tissue at the lower right. The placenta is formed from both the embryonic tissues and the lining of the uterus. The placenta eliminates the need for a yolk sac- the balloon floating off to the lower left, which furnished nurishment up to this time. |
