Granulocytic cells

The granulocytes are classified as Neutrophils, Eosinophils and Basophils on the basis of cellular morphology and cytoplasmic staining characteristics.granulocytes

a) Neutrophils:

  • It has a multi-lobed nucleus & granulated cytoplasm that stains with both acid & basic dyes.
  • It is often called a "Poly-morphonuclear leukocyte'(PMN)
  • These are produced by hematopoiesis in the bone marrow, which are released into the tissues, where they have a life span of only a few days.
  • Movement of circulating neutrophils into tissues called "Extravasation".
  • The neutrophils contains primary & Secondary granules:

Larger, denser primary granules

Peroxidase, Lysozyme, Various hydrolytic enzymes

Smaller, secondary granules

Collagenase, Lactofemn & Lysozyme

  • Both primary & secondary granules are fuse with phagosomes.
  • The cells exhibit a larger "Respiratory Burst" than macrophages & express higher levels of "defensins" than macrophages do.

b) Eosinophils:

  • The cells are motile phagocytic cells that can migrate from the blood into the tissue spaces.
  • It has a bi-lobes nucleus & a granulated cytoplasm that stains with the acid dye "Eosin" red (hence its name).
  • Play a significant role like phagocytic role like macrophages.
  • The secreted contents of eosinophilic granules may damage the parasite membrane.

c) Basophils:

  • It has a lobed nucleus and heavily granulated cytoplasm that stains with the basic dye "methylene Blue".
  • These are nonophagocytic granulocytes, which release pharmacologically active substances from their cytoplasmic granules. These substances play a major role in certain "Allergic responses".

Popular posts from this blog

Null cells

Null cells are lymphocytes with cytotoxic properties. They are neither B-cells not T cell. They are intermediate between T and B cells. They form less than 3%. There are two types of Null cells namely, Natural Killer Cells (NK cells) and Killer Cells . Natural Killer Cells: NK cells are a group of null cells. They form the third population of lymphocytes. The NK cells have 2 or 3 large granules in the cytoplasm. Hence they are also Large Granular Lymphocytes (LGL). They have a kidney shaped nucleus. The NK cells kill the target cells without the aid of antibody or complement. So they are antibody independent. They destroy the cancer cells and cells infected with herpes and mumps virus . They are activated by Interferons and I nterleukins-2. Killer Cells (K cells): Killer cells are antibody dependent. These cells possess Fc receptors for binding with IgG antibodies. Hence they can bind with cells coated with IgG antibodies and can kill them. These cells can combine
Read more

Lymph node

Image
Lymph nodes are encapsulated bean-shaped structures containing a reticular network placed with lymphocytes, macrophages & dendritic cells. The overall architecture of a lymph node supports an ideal micro environment for lymphocytes to effectively encounter and respond to trapped antigens. The lymph node can be divided into three roughly concentric regions based on morphology: Cortex: The Cortex contains lymphocytes (mostly B-cells), macrophages & follicular dendritic cells arranged in primary follicles. This cortex region some times referred to as "Thymus-independent area. Medulla: It is innermost layer of lymph node P ara-cortex: Beneath the cortex, which is populated largely by T-Lymphocytes and also contains interdigitating dendritic cells thought to have migrated from tissues to the node. These interdigitating dendritic cells express high levels of class n MHC molecules, which are necessary for presenting antigen to T H -cells. These paracort
Read more

Thymus

Image
The thymus is a flat, bi-lobed organ situated above the heart. Immature T-cells are simply referred as "Thymocyte", these are densely packed outer compartment (or) cortex of the thymus lobule. Some of the thymic epithelial cells in the outer cortex, called "nurse cells", have long membrane extensions that surround as many as so thymocytes, forming large multicellular complexes The average weight of the thymus is 70 grams in infants; its age dependent involution levels an organ with an average weight of only 3 grams in the elderly. Explanations about Thymus: The thymus covered by a fibrous capsule . It is formed of two lobes. Each lobe of the thymus is organized into lobule which is separated from one another by septa called trabeculae. With in each lobule, the cells are arranged into an outer cortex and an inner medulla. The cortex is tightly packed with proliferating immature lymphocytes while the medulla contains more mature cells. As
Read more