Basophils- Definition, Structure, Immunity and Functions


What are Basophils? Definition of Basophils Basophils are nonphagocytic granulocytes that are the least common leukocytes occurring in the blood circulation and are critical to the immune response against parasites. Basophils are similar to eosinophils in that these are produced in response to parasitic infections; however, in the absence of parasitic infections, basophils are involved in allergy symptoms. Even though basophils account for a small percentage (0.5%) of the total circulating blood cells, the number can increase rapidly in response … Read more

Eosinophils- Definition, Structure, Immunity and Functions


What are Eosinophils? Definition of Eosinophils Eosinophils are motile phagocytic cells that play an important homeostatic role in providing defense against parasitic infections. Eosinophils are bone marrow-derived granulocytes that remain in the bloodstream for a shorter period of time and mostly reside in tissues. The functions of eosinophils are multifaceted, including antigen presentation, the release of peptides, lipids, and cytokine mediators. However, these can also be a part of malignant neoplasms and autoimmune conditions, and connective tissue disorders. Eosinophils represent … Read more

Vesicles- Definition, Structure, Functions and Diagram

Vesicles- Structure, Types, and Functions

Vesicles Definition Cells must be able to move molecules, digest particles, and secrete materials in order to survive. For many cellular functions, vesicles are used. It is a small, spherical compartment that is separated from the cytosol by at least one lipid bilayer. Many vesicles are made in the Golgi apparatus and the endoplasmic reticulum or are made from parts of the cell membrane by endocytosis. Because vesicles are made of phospholipids, they can break off of and fuse with … Read more

Endocytosis and Exocytosis (Endocytosis vs Exocytosis)

Endocytosis and Exocytosis (Endocytosis vs Exocytosis)

Image Source: Freepik Company S.L. Similarities of Endocytosis and Exocytosis Endocytosis and exocytosis mechanisms are forms of Active Transport, both using energy to transport particles in and out of the cell. They both have different types similar in that they both transport materials across the cell membrane by forming vesicle pores. Differences between Endocytosis and Exocytosis Characteristic Endocytosis Exocytosis Definition Endocytosis is a cellular mechanism where a cell internalizes substances from the external environment. These substances undergo certain processes of … Read more

Mast Cells- Definition, Structure, Immunity, Types, Functions

Mast Cells

What are Mast Cells? Definition of Mast Cells Mast cells are cells of the immune system of the hematopoietic lineage that remain widely distributed in vascularized tissues throughout the body. Mast cells, unlike other immune cells, do not remain in the blood but remain localized in mucosal and epithelial tissues throughout the body. These are among the first cells to interact with environmental antigens and invading pathogens or microorganisms. Mast cells are thus considered one of the first cells of … Read more

Dendritic Cells- Definition, Structure, Immunity, Types, Functions

Dendritic Cells

What are Dendritic Cells? Definition of Dendritic cells Dendritic cells are key antigen-presenting cells of the immune system that inform other effector immune cells to fight against invasive pathogens. These are also called professional antigen-presenting cells as these present antigens or parts of antigen to the receptors on different immune cells in order to elicit an immune response against them. Dendritic cells represent a distinct type of white blood cells capable of alerting the immune system about the presence of … Read more

Macrophages- Definition, Structure, Immunity, Types, Functions


What are Macrophages? Macrophages Definition Macrophages are mononuclear cells functioning as professional phagocytes in order to remove dying, dead or harmful pathogens. Macrophages are a type of white blood cell of the immune system where they engulf and digest particles that are detected as antigens by other blood cells. These are larger phagocytic cells that occur in essentially all types of tissues, and their structure and shape depend on the stage of maturation of the cells. Macrophages found in different … Read more

Natural Killer (NK) Cells- Definition, Structure, Immunity, Functions

Natural Killer (NK) Cells

What are Natural Killer (NK) Cells? Definition of NK Cells Natural killer (NK) cells are a group of innate lymphocyte cells with cytolytic activity against virus-infected cells and physiologically stressed cells like tumor cells. Initially, NK cells were described as larger granular lymphocytes with cytotoxic activity against tumor cells. However, these have since been recognized as a separated lineage of lymphocytes with cytotoxicity as well as cytokine-producing effector functions. Natural killer cells are a part of the group consisting of … Read more

Telophase in Mitosis and Meiosis (Telophase I, II)

Telophase in Mitosis and Meiosis

What is Telophase? Telophase is the fifth phase of mitosis and the final phase of meiosis as well. In meiosis, there are two phases of telophase I and telophase II. This is the stage of separation of duplicate genetic materials that are carried in the cell nucleus of the parent cells. They end up forming two identical daughter cells. Telophase starts after replication when the paired chromosomes are separated and have been pulled to the opposite poles of the cell. … Read more

Storage Granules- Definition, Structure, Functions and Diagram

Storage Granules

Storage Granules Definition Storage granules are membrane-bounded vesicles containing condensed materials. They are also known as zymogen granules or condensing vacuoles. Storage granules are an important component of metabolism in many organisms spanning the bacterial, eukaryotes and archaeal domains. These granules are the parts of the cell that store the cell’s energy reserves as well as other important metabolites. Figure: Diagram of Storage Granules. Image Source: Slide Player Structure of Storage Granules Storage granules are simple small organelles, bounded by … Read more