The macrophages

Macrophages derived from bone-marrow precursors and parent monocytes in the peripheral blood are multi-functional cells of the innate immune system. They play a pivotal role not only in the generation of inflammatory mediators and in the regulation of the innate and adaptive immunity, but also contribute to the resolution of inflammation and the reestablishment of homeostasis.

These cells were first recognized by Elia Metchnikoff in 1882 in the larvae of starfish upon insertion of thorns of tangerine tree and later in Daphnia magna or common water flea infected with fungal spores as cells responsible for the process of phagocytosis of foreign particles. He described macrophages as a large cell with marked phagocytic ability found in most connective tissues and body fluids throughout the animal kingdom.

Many tissue macrophages are prenatally established during embryonic development from progenitors derived from the yolk sac or fetal liver and in the steady state they are maintained independently from the bone marrow-derived monocytes.

Macrophages reside in every tissue of the body and exhibit a great functional diversity. Depending on the tissue in which they reside, macrophages possess different shapes, e.g., Kupffer cells in the liver or Langerhans cells in the skin. In mice, macrophages present in many tissues, including skin, liver, kidney, and brain, originate from the yolk sac or the fetal liver.

As one of the most effective cell types in the emergency response system of the human body, macrophages modulate host defense, inflammatory processes, and homeostasis.

With powerful abilities of cell engulfment, antigen presentation and cytokine secretion, macrophages govern the initiation and resolution stages of innate and adaptive immunity.

Macrophages are equipped with a broad-range of pattern-recognition receptors (PRRs), which are required for the production of an array of inflammatory and immunosuppressive cytokines, and the uptake of cellular debris and pathogenic material.
The macrophages

The meaning of eukaryote

Eukaryotic cells have membrane-bound organelles (“little organs”). The cell’s nucleus for example is an organelle. Organelles are scattered throughout the cell’s cytoplasm.

All organisms, expect bacteria, are made up of eukaryotic cells. Protozoa, algae, fungi, higher plants and animals are eukaryotic. The nuclear material does not mix with the cytoplasm.

Nucleus serves two important functions. First, it keeps the cell’s genetic material – its DNA – safe and sound. Isolated in its own compartment, the cell’s DNA stays separated from the bustling activity of the cytoplasm and from metabolic processes that might damage it.

Eukaryotic cells are larger and more complex than prokaryotic cells. In addition to a nucleus, these and most other eukaryotic cells contain an endomembrane system (ER, vesicles, and Golgi bodies), mitochondria, and a cytoskeleton, which is a dynamic “skeleton” of proteins. They perform specific cellular functions, for example, respiration and photosynthesis.
The meaning of eukaryote

What is prokaryote cell?

Classification of prokaryotes has long been based on the same hierarchical systems on which Linnaeus based his nomenclatural system applied initially to plants and animals. Most of the earth’s prokaryotes are found in the open ocean and in soil.

Prokaryotes are believed it be abundant in environment where eukaryotic organisms are absent or very rare, which they subsurface (e.g. below 8 m for the terrestrial environment and below 1 cm for ocean sediment).

Prokaryotic cell

Bacteria are very small organisms, typically consisting of one cell. Prokaryotic cell does not contain a membrane-bound nucleus. In eukaryotic cells, such as those of plants and animals, the nucleus controls the cell functions and contains its genes.

Each prokaryotic cell is surrounded by a plasma membrane. The cell has no subcellualr organelles, only infoldings of the plasma membrane called mesosomes.

Prokaryotes lack diagnostic morphological characteristics and are asexual organisms that exchange genetic material in unique and unusual ways compared to eukaryotes.
What is prokaryote cell?