The key difference between granulocytes and agranulocytes is that the granulocytes contain cytoplasmic granules while the agranulocytes do not contain cytoplasmic granules.
Blood contains different components. Among them, white blood cells or leukocytes are one of the major cells that involve in defence and immunity. They serve as the main cellular part of the blood. Furthermore, they are larger than red blood cells but found in low numbers compared to them. Also, there are two types of white blood cells. Namely, they are the granulocytes and agranulocytes. This classification depends on several factors such as the presence or absence of cytoplasmic granules, nuclear shape, affinities for laboratory stains or dyes, etc.
Moreover, unlike red blood cells, white blood cells can exit the blood by assuming amoeba-like behaviour to wriggle through narrow capillary pores, and do their function in various tissues. However, the main function of leukocytes is to defend the body against infective pathogens and foreign materials. Thus, leucocytes and their derivatives, along with certain plasma proteins are responsible for making the immune system, in many higher organisms.
CONTENTS
1. Overview and Key Difference
2. What are Granulocytes
3. What are Agranulocytes
4. Similarities Between Granulocytes and Agranulocytes
5. Side by Side Comparison – Granulocytes vs Agranulocytes in Tabular Form
6. Summary
What are Granulocytes?
Granulocytes are a type of white blood cells that contain cytoplasmic granules. The production of granulocytes occurs in red bone marrow in vertebrates. Also, they can be easily differentiated by the colour of their granules when stained with Wright’s stain. Furthermore, there are three types of granulocytes. Namely, they are neutrophils, eosinophils, and basophils.
Figure 01: Granulocytes
Out of them, neutrophils are the most numerous white blood cells that contain nuclei divided into one to five lobes. The main function of neutrophil is to destroy pathogens by phagocytosis. Eosinophils contain irregularly shaped nuclei with two lobes, and course, uniform, round or oval-shaped granules in their cytoplasm. Also, eosinophils increase in great numbers during the allergic conditions and are important to ingest and detoxify foreign substances. On the other hand, basophils represent the least numerous white blood cell type and contain centrally located, S-shaped nuclei. They perform phagocytosis, and they release herpin and histamine and promote the inflammatory responses in organisms.
When considering the total amount of white blood cells, granulocytes account for 65 % compared to agranulocytes. And also these granulocytes contain an important enzyme that is not present in agranulocytes.
What are Agranulocytes?
Agranulocytes or mononuclear leukocytes are a type of leukocytes that lack visible cytoplasmic granules. Since these cells do not have granules in their cytoplasm they do not respond to Wright’s stain. Moreover, there are two types of agranulocytes. Namely, they are monocytes and lymphocytes.
Figure 02: Agranulocytes
Here, the monocyte is the largest white blood cell type and contains a horseshoe-shaped nucleus. Looking at their functions, the main function of a monocyte is to carry out phagocytosis of cellular debris and foreign particles. A lymphocyte is normally the second numerous white blood cells type and contains one large, spherical nucleus. Also, there are two types of lymphocytes. Namely, they are the T lymphocytes and B lymphocytes. T lymphocytes directly attack infected cells, and they do not make antibodies. Unlike T lymphocytes, B lymphocytes produce antibodies and release into the bloodstream to circulate and attack foreign particles. Monocytes make up 1-7 %, while lymphocytes make up 15 to 30 % of total white blood cells in an adult human.
What are the Similarities Between Granulocytes and Agranulocytes?
- Granulocytes and Agranulocytes are white blood cells.
- Both act as immune cells during the defence mechanisms.
- They are present in the bloodstream.
What is the Difference Between Granulocytes and Agranulocytes?
Granulocytes and agranulocytes are two major types of white blood cells. As the names indicate, the difference between granulocytes and agranulocytes is the presence and absence of cytoplasmic granules. Granulocytes have cytoplasmic granules while agranulocytes lack granules. Granulocytes contain segmented nuclei while agranulocytes contained nonsegmented nuclei. Hence, they are referred as polymorphonuclear leukocytes and mononuclear leukocytes respectively. Therefore, we can consider this is another difference between granulocytes and agranulocytes. Furthermore, they differ from the origin as well. Granulocytes originate in the bone marrows while agranulocytes originate in the lymphoid.
The below infographic gives more details on the difference between granulocytes and agranulocytes.
Summary – Granulocytes vs Agranulocytes
Leukocytes or white blood cells are two types namely granulocytes and agranulocytes. Granulocytes have cytoplasmic granules which can be stained by Wright’s stain. In contrast, agranulocytes lack cytoplasmic granules. Thus, this is the key difference between granulocytes and agranulocytes. Furthermore, granulocytes have a lobed nucleus while agranulocytes do not have a lobed nucleus. Another difference between granulocytes and agranulocytes is the origin. Granulocytes originate from the bone marrow of human while agranulocytes originate from the lymphoid. When considering the percentage of the granulocytes and agranulocytes from the total white blood cells, granulocytes account for 65% of the total leukocytes while agranulocytes account for 35%. Thus, this is the summary of the difference between granulocytes and agranulocytes.
Reference:
1.Boundless. “Boundless Anatomy and Physiology.” Lumen. Available here
Image Courtesy:
1.”1907 Granular Leukocytes”By OpenStax College – Anatomy & Physiology, Connexions Web site. Jun 19, 2013., (CC BY 3.0) via Commons Wikimedia
2.”Figure 40 02 03ab”By CNX OpenStax , (CC BY 4.0) via Commons Wikimedia