Haemolymph node - an immunomorpholoigcal organ: modeling the haemolymph node by allografting renal tissue in the rat.

There is no authoritative identification of the attributes of the haemolymph node since Gibbes first described it in 1884. Early literatures showed that it was found near the kidney in human and animals with the characteristics of numerous erythrocytes in sinuses. Subsequent studies were mainly focused in the field of anatomy and histology, such as the source, distribution and quantity of erythrocytes in sinuses. Recent articles mentioned that the emergence of the haemolymph node was related to immunity, but there was no strong evidence to support the hypothesis. Therefore it is still uncertain whether the haemolymph node is an organ of anatomy, histology or immunology. It has been found that the development of the haemolymph node can be elicited in the parathymic area by stimuli such as Escherichia coli, allogeneic breast cancer cells and renal tissue that were injected/transplanted into the tail of rats in our pilot studies. In this study, the model of the haemolymph node was established by transferring the allogeneic renal tissue in the rat. Intrasinusoidal erythrocytes of the node were the component for producing a red macroscopic appearance, while macrophage-erythrocyte-lymphocyte rosettes were the major immunomorphological changes, which reflects the immune activity against the invasion of the allogeneic tissue within the node. Therefore the haemolymph node is an immunomorphological organ.