Scientific journal
European Journal of Natural History
ISSN 2073-4972


Petrenko V.M.
More centure bone marrow was considered as part of bones, spleen was classified to alimentary system, thymus - to endocrine glands, lymph nodes - to lymphatic system. The first International Histological Nomenclature contained division «Haemopoietic organs» - bone marrows, spleen, thymus. In new International Anatomical and Histological Terminologies all seats of haemopoiesis are united into lymphoid system by their immunopoetic function. This aggrigate can be to definite only as lymphoid apparatus. Bone marrow, aggregated and solitary lymphoid nodules are not independent organs. Red bone marrow and spleen are mixed haemopoietic organs by their structure with predominance of myeloid tissue, which form in connection with venous sinuses. Thymus and tonsils arise as congestion of epithelial and mesenchymal cells, later they transformate into lymphoepithelial organs. Lymph nodes arise as interweavings of lymphatic and blood vessels by means of invagination of blood vessels into the lymphatics, connective tissue between them transformates into lymphoid tissue. I think that it shoud be to discern «haemopoeitic organs», which are divided on myeloid-lymphoid (bone marrow, spleen) and lymphoid (thymus, lymph nodes, tonsils). Myeloid-lymphoid organs have row of important structural features - extralymphatic (parenchyma don´t connects with lymphatic bed, it is related to thymus and tonsils too), sinusoidal (venous sinuses as paths away of blood cells), periarterial (by localization of lymphoid elements). Lymphoid organs contain high endothelium venules - paths of lymphocytes recirculation between primary and secondary lymphoid organs. Cortex of thymus looks like spleen on paths of lymphocytes influx in the organ.