The ability of the many cell types within the adult blood system to be constantly replenished and renewed from hematopoietic stem cells is an interesting problem in development and differentiation and has led to questions concerning how, when and where these stem cells for the adult hematopoietic system are generated within the embryo. During embryonic development many mature hematopoietic cell...

The adult hematopoietic system of mammals is a dynamic hierarchy of cells with the hematopoietic stem cell at its foundation. During embryonic development, the source and expansion potential of this cell remain unclear. Two sites of hematopoietic activity, the yolk sac and aorta-gonad-mesonephros (AGM) region, function in mouse ontogeny at the pre-liver stage of hematopoiesis. However, cellular...

Many investigators have used xenogeneic, especially murine stromal cells and fetal calf serum to maintain and expand human stem cells. The proliferation and expansion of human hematopoietic stem cells in ex vivo culture were examined with the goal of generating a suitable protocol for expanding hematopoietic stem cells for patient transplantation. Using primary fetal liver cells, we established...

The aim of this study was to isolate mouse embryonic stem cells from late blastocyst stage embryos and to use them as a model system for the study of hematopoietic induction outside the embryo by coculturing of embryonic stem cells with bone marrow stromal cells. Blastocyst stage embryos from pregnant NMRI mice were obtained and cultured for 1-2 days in DMEM medium. The inner cell masses formed...

This article has summarized parts of certain publica­tions about changes of hematopoietic elements, specially erythroid, during embryonic and fetal to the third postnatal life. The main purpose of this article is to familiarize medical students with the physiological characteristics of the blood system, chiefly in the first trimenon of postnatal life.  It is also aimed to prevent many incorrec...

The etiology of the age-associated pathophysiological changes of the hematopoietic system including the onset of anemia, diminished adaptive immune competence, and myelogenous disease development are underwritten by the loss of normal homeostatic control. As tissue and organ homeostasis in adults is primarily mediated by the activity of stem and progenitor cells, it has been suggested that the ...

thalassemia is an autosomal recessive disorder associated with defective synthesis of the α- or β-chain of hemoglobin. for β-thalassemia major patients, therapeutic options are either monthly red cell transfusions and chelation therapy or allogeneic stem cell transplant. stem cell transplant is the only curative approach and success is inversely correlated with the degree of iron overload and h...

Blood cells are constantly produced in the bone marrow (BM) of adult mammals. This constant turnover ultimately depends on a rare population of progenitors that displays self-renewal and multilineage differentiation potential, the hematopoietic stem cells (HSCs). It is generally accepted that HSCs are generated during embryonic development and sequentially colonize the fetal liver, the spleen, ...