Haematopoiesis and Regeneration: Changes in the Liver, Spleen, Bone Marrow and Hepatic Iron Content during Tail Regeneration in the Scincid Lizard, Mabuya Carinata (Boulenger)

Abstract

In response to the observed changes in blood during tail regeneration, a detailed histophysiological study of the haemopoietic organs such as liver, spleen and bone marrow was undertaken. During regeneration, all three organs were found to undergo histophysiological changes. Increased haemopoietic activity in the marrow and hyperplasia of the white pulp were the important changes shown by the bone marrow and spleen respectively. In the liver, the most marked effect appeared to be the formation of large numbers of lymphocytopoietic nodules. Another interesting observation was the influx and destruction of red blood cells both in the liver and spleen, once during the early regressive phase and once during the late progressive phase of regeneration. An attempt is made to correlate these changes in the three haemopoietic organs with the possible involvement of lymphocytes in the formation of a regeneration blastema and a possible haemoglobin transition during regeneration. The present observations are in concordance with the previous observations on blood.

Immunolocalization indicates that both original and regenerated lizard tail tissues contain populations of long retaining cells, putative stem/progenitor cells

“…Together with the previous studies on the fluctuation of blood cell types during tail regeneration in lizards (Alibardi, ; Hiradhar et al, ; Ramachandran et al, ; Shah et al, ), this study has indicated that the bone marrow and blood vessels supply the granulation tissue of the preblastema with circulating and still maturing blood cells that are utilized for immunitary defence before mesenchymal cells replace these hematogenous cells in the growing blastema (Alibardi, ; Alibardi and Sala, ).…”

“…During tail regeneration, not only in the circulating blood and in the blastema but also in hemopoietic organs such as spleen and liver, there is a production of many blood cells (Ramachandran et al, ; Shah et al, ). In the liver, nodules of lymphocytes are generated (Ramachandran et al, ), and in the spleen, the white pulp increases (Shah et al, ).…”

“…During tail regeneration, not only in the circulating blood and in the blastema but also in hemopoietic organs such as spleen and liver, there is a production of many blood cells (Ramachandran et al, ; Shah et al, ). In the liver, nodules of lymphocytes are generated (Ramachandran et al, ), and in the spleen, the white pulp increases (Shah et al, ). The fate of blood cells in the blastema is not known, although most granulocytes die and are removed during the first week after tail amputation, whereas macrophages and lymphocytes appear to remain longer among mesenchymal cells (Alibardi, ; Alibardi and Sala, ).…”

“…The fate of blood cells in the blastema is not known, although most granulocytes die and are removed during the first week after tail amputation, whereas macrophages and lymphocytes appear to remain longer among mesenchymal cells (Alibardi, ; Alibardi and Sala, ). Although suggested (Hiradhar et al, ; Ramachandran et al, ; Shah et al, ), no proof that blood cells can transform into mesenchymal‐like cells of the blastema has been provided. The definitive direct documentation of the transformation of connective, muscle, or blood cells into mesenchymal elements of the blastema, requires further experiments.…”

“…In conclusion, the numerous blood cells present on the stump and early blastema derive from the migration of immature elements produced in the bone marrow through blood vessels or from the extravasation from the damaged vertebrae of hemopoietic elements. Hematogenous cells might arrive into the blastema also from other hemopoietic organs, such as spleen and liver (Ramachandran et al, ; Shah et al, ). These hemopoietic cells are later replaced by mesenchymal cells that, in part, derive from the sparse LRCs detected in the tail stump, especially in connective tissues and muscles, suggesting that they represent stem/progenitor cells.…”