Hematology and Oncology

This section incorporates both normal and abnormal blood constituents.

Links to Erythrocytes, Thrombocytes, Heme Malignancies, and Lab Tests

Hematopoietic Lineages

All cells of the blood arise from one hematopoietic lineage via different pathways. Each cells type has a specific purpose in the body. You can find a diagram here, or a description below.

Hematopoietic Stem Cells

Gives rise to all blood cells. These are the cells that are transferred in a Bone Marrow Transplant (BMT). Different growth factors cause maturation down different pathways but they will not be mentioned here.

Lymphoid Progenitor

Gives rise to lymphocytes: B cells, T cells, and Natural Killer (NK) cells (often aren't included on hematopoiesis diagrams). These cells are mainly involved with active immunity, with NK cells also functioning in innate immunity. They cannot be distinguished on a blood smear.

B Cell Lineage

The main cells of the humoral response. They produce antibodies (AKA immunoglobulins AKA gammaglobulins), which bind to antigens.

T Cell Lineage

The main cells of the cell-mediated response. They activate other immune cells as well as killing infected cells.

Myeloid Progenitor

Gives rise to non-lymphoid cells (everything else).

Erythrocyte Lineage

This lineage eventually results in red blood cells, otherwise known as erythrocytes. Their main role is to transport oxygen from the lungs to the tissues using hemoglobin. Immature erythrocytes, known as reticulocytes are an important indicator of erythropoiesis but require a special stain for visualization. Read more about erythrocytes here.

Megakaryocyte Lineage (Platelets)

This lineage produces giant cells called megakaryocytes, which produce cell fragments called platelets (thrombocytes). Their main role is to produce and maintain clots. Read more about thrombocytes here.

Granulocyte Lineage (Eosinophils, Basophils, Neutrophils, and Monocytes)

This lineage produces all non-lymphoid white blood cells. One half of the lineage produces eosinophils and basophils, with the other half producing neutrophils and monocytes. Immature neutrophils, known as bands, are an important indicator of infection.