Cell morphology refers to the physical characteristics and observable traits of cells. It's a subfield of cytology, which is the study of cells in general.
This book is an atlas of morphological characteristics of
pathological cells in blood and bone marrow. Major emphasis is placed on the anatomical characteristics of individual cells in the various stages of their maturation. See
This reading note only focuses on the atlas’ information on
normal cells and do not encompass the part of the book that talks about
This reading note is also focused mainly on:
- Terminologies … very basic ones indeed, for at the time of writing, I have the biology knowledge of a new-born baby.
- Pictures … diagrams and pictures of the cell developmental process, and visual pictures of each kind cell in a non-pathological smear.
My goal is to be able to look at a
So for each of the specific cell types, I created this exercise for myself to look at the BMA slides from the DeepHeme demo, and find examples and take screenshots of examples.
Self-renewal refers to the process by which a cell divides to produce two cells, at least one of which maintains the undifferentiated state of the parent cell. This process allows a population of cells to maintain its number over time.
This term is often used in the context of stem cells. A key property of stem cells is their ability to self-renew, or produce copies of themselves, while maintaining their undifferentiated state. This is what allows stem cells to contribute to the development, growth, repair, and maintenance of tissues throughout the lifetime of an organism.
For example, in the bone marrow, hematopoietic stem cells divide to produce more stem cells (self-renewal) as well as progenitor cells that will differentiate into the various types of blood cells (differentiation). This balance between self-renewal and differentiation is crucial for maintaining healthy tissue function.
When the balance is disrupted, it can lead to problems. If the stem cells differentiate too much without sufficient self-renewal, the tissue might not be able to replace cells that are lost due to wear and tear or injury. On the other hand, if self-renewal occurs too much without enough differentiation, it can result in an overgrowth of undifferentiated cells, which is a characteristic of cancer.
Progenitor cells are stem cells that are not fully
A "precursor cell compartment" typically refers to the collection or population of cells that are destined to become a particular cell type. These cells have already been committed to a specific lineage or fate (e.g., a neural precursor cell is already committed to the neural lineage) but have not yet undergone the final steps of differentiation to reach their mature state.
Just look at this nice picture!
Cellular commitment, also often referred to as lineage commitment, is a term used in developmental biology to describe the point in the differentiation process at which a cell becomes destined to develop into a specific cell type or tissue.
"Ameboid" or "amoeboid" is a term that describes a specific type of movement or behaviour that some cells and organisms exhibit. The word comes from the name "amoeba," which is a type of single-celled organism that moves in this way.
So, what does ameboid movement look like? Well, imagine a blob of jelly that can stretch and squish itself to move around. This is essentially how amoeboid movement works. The cell or organism extends part of its body to form something like an arm, called a pseudopod ("false foot"), then flows into this extension to move forward. This is an effective way for these organisms or cells to move around in their environments, especially when the terrain is irregular.
- Cytokines: Cytokines are small proteins that are released by cells and have a specific effect on the interactions and communications between cells. They play essential roles in the body and are involved in various biological processes, such as immune responses, inflammation, and the healing of wounds. Examples of cytokines include interleukins, interferons, and tumor necrosis factors. They are crucial for cell signaling and can stimulate the movement of cells towards sites of inflammation, infection, and trauma.
- Growth Factors: Growth factors are a special type of protein that cells release to communicate with each other. They are responsible for helping to control cell growth, proliferation, and differentiation. They're very important in biology and medicine, because they help to regulate a variety of cellular processes. For example, epidermal growth factor (EGF) stimulates cell growth and wound healing, and erythropoietin (EPO) stimulates the production of red blood cells.
- Receptor Systems: Receptor systems refer to the proteins located either on the surface of or inside cells that receive signals from outside the cell. When these receptors are activated (usually by a molecule like a cytokine or a growth factor binding to them), they trigger a response inside the cell. This could be anything from causing the cell to grow, to changing what genes the cell is expressing, to causing the cell to die. Receptors are crucial for cells to respond appropriately to their environment and communicate with each other.
In summary, cytokines, growth factors, and receptor systems are all involved in cell communication. Cytokines and growth factors are proteins that send signals, while receptor systems receive these signals and trigger responses inside the cell. They all play crucial roles in maintaining the body's health and responding to diseases or injuries.
Hematopoiesis and Blood Cells
The Wright stain is a type of stain that's used in the laboratory to help visualize and differentiate cells, especially blood cells, under a microscope. Named after James Homer Wright, who developed the technique in the early 1900s, the Wright stain is particularly useful for examining blood smears and bone marrow samples.
When cells are stained with the Wright stain, different types of cells take up the stain differently and show different colors. This allows scientists or doctors to distinguish between different types of blood cells, such as red blood cells, white blood cells, and platelets. The stain can also highlight structures within the cells, such as the cell nucleus or any granules in the cell's cytoplasm.
Specifically, the stain typically colors the cell nuclei purple-blue and the cytoplasm pink-orange, while granules in the cytoplasm of certain white blood cells can show up as dark purple spots.
By using the Wright stain, doctors and scientists can identify abnormalities in the cells, such as changes in size, shape, or color, which could indicate diseases like anemia, leukemia, or other blood disorders. This makes it a very important tool in diagnostic medicine, particularly in hematology, the study of blood.
- Neutrophils: These are the most common type of white blood cells in our blood. They are filled with granules that contain a variety of enzymes and antimicrobial proteins. When stained for microscopic examination, neutrophil granules do not take up either acidic or basic dyes very strongly, and so appear a
neutralpink color, hence the name "neutrophil". Neutrophils are typically the first responders to a site of inflammation or infection, where they engulf microbes in a process called phagocytosis.
- Eosinophils: Eosinophils are named for their affinity for
eosin, an acidic dye, which gives their granules a bright red or pink color when viewed under a microscope. These granules are packed with a variety of substances that are particularly effective against parasites, like worms, that are too big for a single white blood cell to engulf. Eosinophils also play a role in allergic reactions, where they can contribute to inflammation and tissue damage.
- Basophils: These are the least common of the white blood cells. Basophil granules are filled with histamine and other substances that can be released to initiate an inflammatory response, and they stain a dark blue or purple color with
basicdyes. Basophils play a key role in allergic reactions. When activated, they release their granules into the surrounding tissue, which can lead to the redness, swelling, and itching associated with allergies.
This is a description of
Yes, erythropoiesis can be considered a subset of myelopoiesis (in the broad sense).
Erythropoiesis refers specifically to the process of red blood cell (erythrocyte) production, while
However, we will use
This is because the process of erythropoiesis and myelopoiesis (narrow-sense) are regulated by different growth factors and conditions in the body, even though both occur in the bone marrow, and a clear distinction and separate consideration is useful.
First, the hematopoietic stem cell turns into a cell called a myeloid progenitor. This is a more specialized cell that can become several different types of cells, including a type of white blood cell called a monocyte.
The monocytes then leave the bone marrow and enter our bloodstream. They circulate in the blood for about one to three days. Then they move into different tissues throughout the body, like our skin, lungs, and brain.
Once they're in the tissues, the monocytes mature into macrophages. Each tissue has a slightly different type of macrophage, but they all have the same main job: to gobble up harmful things and help keep our bodies healthy.
See the respective hyperlinks.
Lymphopoiesis and myelopoiesis are two processes that our bodies use to create different types of white blood cells, which are crucial players in our immune system.
- Lymphopoiesis: This process is all about creating lymphocytes, a type of white blood cell. Lymphocytes include T cells, B cells, and natural killer (NK) cells. These cells are crucial for our adaptive immune system, which is the part of our immune system that learns and remembers specific pathogens (like viruses or bacteria) to fight them off more effectively if they come back. Lymphopoiesis primarily occurs in the bone marrow and the thymus, a gland situated behind your sternum and between your lungs.
- Myelopoiesis: This process, on the other hand, involves the production of other types of white blood cells including neutrophils, basophils, eosinophils (collectively called granulocytes), as well as monocytes and macrophages. These cells are part of our innate immune system, which provides a rapid, but nonspecific response to pathogens. These cells also play a crucial role in inflammation and allergic reactions. Myelopoiesis primarily takes place in the bone marrow.
So in simple terms, both lymphopoiesis and myelopoiesis are processes that create different types of white blood cells. Lymphopoiesis results in lymphocytes, which are key players in the adaptive immune system, while myelopoiesis results in other types of white blood cells, like neutrophils and monocytes, which are involved in the innate immune system. Both processes are critical to maintain a healthy and functioning immune system.