Origin of “white cells"

Just to briefly understand them better, let’s talk about where the “white cells'' are formed. These cells are born and specialize inside the bone marrow (from long bones, like the femur) in a process called haemopoiesis. 

From one multipotential hematopoietic stem cell in our bone marrow (from long bones; like the femur) the other “white cells” are differentiated, and they start to specialize. We call the two main lineages “myeloid” and “lymphoid''.

Fig 1 - Haemopoiesis. Myeloid lineage (left) and lymphoid lineage (right)

Each lineage follows a specific path of specialization when they enter the blood system.

From the myeloid lineage basophiles, neutrophils (the most common “white cell”), eosinophils and macrophagues are formed.

From the lymphoid lineage, they travel to the tissues/organs of our immune system (lymphatic nodes, timus, spleen and MALT - mucosa-associated lymphoid tissue).

Fig. 2 - Rabbit lymph node follicles. 
HE | 4X | MoticEasyScan 

Fig 3 - Polymorphous lymphoid lineage cells in a lymphatic node.
HE | 40X | MoticEasyScan 

In the next posts, we will explore what can happen to these cells if they become their “malignant” variant (leukemia, lymphoma, myeloma…).

Let’s get ready for more next week!