Due to difficulty defining lymphatic markers, difficulty visualizing vessels with traditional methods, and emphasis on the vascular system, research into the development of the lymphatics is still in its infancy–with many theories still to be proven. Without a doubt, it starts development in week 5, perhaps from the veins or the mesenchyme. Then, in weeks 6-9, sacs are formed in the neck, groin, posterior abdominal wall, and in the gut. Ducts grow and connect the different sacs while lymphatic vessels grow peripherally to the head, neck, arms, gut, and legs. The sacs become the lymph nodes, except for the upper portion of the gut sac: the cisterna chyli. Mesenchymal cells infiltrate the nodes and develop channels, capsule, and node framework. Lymphocytes appear just before birth in the nodes from the thymus. Lymph organs form from mesenchymal cells and clumping of lymph nodules.
So, from week 5 to the final week of gestation, the lymphatic system is developing. A spontaneous mutation at any point, injury to the fetus, a hereditary malformation, or a preterm delivery can all affect the lymphatic system of a child. This deficit can be apparent at birth, or latently appear at any time in their life, depending on where the deficit is … read more