GENESIS OF PRIMARY LYMPHATIC STRUCTURES IN HUMAN
Serial sections of corpses of 57 embryos and 5-11 weeks fetuses stained with hematoxylin-eosin, according to Van Gieson and Weigert were studied. In embryogenesis and early fetal period lymphocollectors of the neck, thoracic and abdominal cavity, axillary and inguinal-femoral regions are consistently represented by the primordia, lymphatic sacks and channels, plexuses with the rudiments of nodes. Lymphatic primordia have a veno-mesenchymal nature and arise on the basis of decaying embryonic veins (cavity) and embryonic connective tissue cells (primary lining). Primary lymphatic structures are formed at the confluence of the primordia and differ from them in size and design of the lymphatic endothelial lining. These include jugular, axillary and subtracheal sacks, pre-vertebral canals (paired thoracic duct), retroperitoneal, retroaortic, common, external and internal iliac and inguinal sacks, retrocaval and retroaortic canals in the lumbar region and those in the celiac trunk branching, upper and inferior mesenteric arteries. In the development of mesenchymal rudiments of the nodes that have an invaginating nature of the formation ( intussusceptive lуmphangiogenesis ) connected between a primary lymphatic structure transformed in multichannel lymphatic plexuses.