What is the Difference Between Myeloblast and Lymphoblast

The main difference between myeloblast and lymphoblast is that the myeloblast differentiates into granulocytes whereas the lymphoblast differentiates into lymphocytes. Furthermore, myeloblast contains granules while lymphoblast does not contain granules. 

Myeloblast and lymphoblast are two types of progenitor cells differentiated from the hemocytoblast during hematopoiesis. Here, hemocytoblast is a multipotent stem cell which can differentiate into several types of precursor cells. 

Key Areas Covered 

1. What is a Myeloblast
     – Definition, Morphology, Pathology
2. What is a Lymphoblast
     – Definition, Morphology, Pathology
3. What are the Similarities Between Myeloblast and Lymphoblast
     – Outline of Common Features
4. What is the Difference Between Myeloblast and Lymphoblast
     – Comparison of Key Differences

Key Terms 

Acute Lymphocytic Leukemia (ALL), Acute Myeloblastic Leukemia (AML), Lymphoblast, Myeloblast, Nucleus

What is a Myeloblast 

Myeloblast is the progenitor cell of granulocytes: neutrophils, eosinophils, and basophils. It is unipotent and differentiates from the multipotent hemocytoblast. Also, the nucleus of a myeloblast can be either S-, C- or V-shaped. Furthermore, the chromatin is less dense; hence, the nucleoli are more prominent. And, the cytoplasm of the myeloblast contains granules.

Besides, myeoloblasts can be stained by myeloperoxidase stain. The presence of Auer rods is one of the significant features of myeloblasts, which helps in the identification of them in a bone marrow smear.

Figure 1: Human Myeloblasts

The development of granulocytes from the myeloblast is called granulopoiesis. The malfunctioning of myeloblasts causes a disease called acute myeloblastic leukemia (AML). It accumulates immature myelocytes in the peripheral blood, causing hematopoietic failure. This leads to anemic conditions, bleeding from orifices as well as recurrent infections.  

What is Lymphoblast 

Lymphoblast is the progenitor cell of T and B lymphocytes. It also differentiates from hemocytoblast. The nucleus of the lymphoblast is round and contains compacted chromatin. As in myeloblasts, it does not contain prominent nucleoli and cytoplasmic granules.  

Figure 2: Blood Cell Lineage

Lymphopoiesis is the differentiation process of lymphoblast into lymphocytes. The acute lymphocytic leukemia (ALL) is the disease condition in which the overproduction of lymphoblasts occurs in the bone marrow. And, it causes recurrent infections like pneumonia.  

Similarities Between Myeloblast and Lymphoblast 

• Myeloblast and lymphoblast are two types of progenitor cells which occur during hematopoiesis. 
• They are large and occur in the bone marrow. 
• Also, both arise from the hemocytoblast. 
• In addition, both are unipotent cells. 
• Furthermore, their differentiation is triggered by cytokines. 

Difference Between Myeloblast and Lymphoblast 

Definition 

Myeloblast refers to a large bone marrow cell which serves as the precursor of myelocytes while lymphocyte refers to another large bone marrow cell which serves as the precursor of lymphoblasts. Thus, this is the main difference between myeloblast and lymphoblast.

Granules 

Another difference between myeloblast and lymphoblast is that the myeloblast contains granules in the cytoplasm while lymphoblast does not contain cytoplasmic granules. 

Shape of the Nucleus 

Furthermore, the nucleus of the myeloblast is either S, C or V-shaped while the nucleus of lymphoblast of rounded.  

Chromatin 

Also, myeloblast contains less condensed chromatin while lymphoblast contains more condensed chromatin. 

Nucleoli 

Moreover, a myeloblast nucleus has prominent nucleoli while a lymphoblast nucleus has less distinct nucleoli. 

Diameter 

Besides, the diameter of a myeloblast is 20 µm while the diameter of a lymphoblast is 15 µm. 

Differentiate into 

Myeloblast can be differentiated into basophils, eosinophils, and neutrophils while lymphoblast can be differentiated into T and B lymphocytes. This is another important difference between myeloblast and lymphoblast.

Pathology 

The malfunctioning of myeloblasts can cause acute myeloblastic leukemia (AML) while the malfunctioning of lymphoblasts can cause acute lymphoblastic leukemia (ALL). 

Conclusion 

Myeloblast is the progenitor cell of myelocytes. The three types of myelocytes are neutrophils, eosinophils, and basophils. A lymphocyte is the progenitor cell of T and B lymphocytes. Both myeloblast and lymphocyte are two types of unipotent cells arisen from hemocytoblast. The main difference between myeloblast and lymphoblast is the type of mature cells arisen from them.

Reference:

1. “Myeloblast.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 20 July 1998, Available Here
2. “Lymphoblast.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 23 June 2011, Available Here

Image Courtesy:

1. “Two myeloblasts with Auer rods” By The Armed Forces Institute of Pathology (AFIP) – PEIR Digital Library (Pathology image database). Image# 404533. (Public Domain) via Commons Wikimedia  
2. “Illu blood cell lineage” (Public Domain) via Commons Wikimedia