Cellular Information and Courses from MediaLab, Inc.

Pappenheimer bodies are seen in the cytoplasm of mature and immature erythrocytes on a Wright's stained smear. They are composed of degenerating cellular remnants, which contain iron. Pappenheimer bodies are most likely caused by accelerated red cell division, or impaired hemoglobin synthesis. Pappenheimer bodies appear as small dark purple granular bodies of varying size frequently clustered in groups of two, three or more near the edge of the cell.

The basis of molecular testing lies in the genetic material of a cell. Both prokaryotic and eukaryotic cells possess nucleic acid. The two types of nucleic acid include deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The foundational building blocks of both DNA and RNA include nucleotide bases of purines and pyrimidines. The unique sequencing of these nucleotide bases found in each strand of DNA or RNA contribute significantly to the language of cells. This cellular based language is responsible for many complex activities within the human body, including the synthesis of proteins.

The Human Immunodeficiency Virus type-1 (HIV) belongs to the Family Retroviridae.In HIV, RNA is the template for the synthesis of DNA. This differs from most cellular biochemistry in which DNA is used as the template for the synthesis of RNA.The enzyme that transcribes the RNA for the synthesis of DNA is called reverse transcriptase.Because of the enzyme's activity, HIV is known as a retrovirus - retro implying reverse.

After penetration of the cell membrane by the gp41, the HIV capsid enters the cell's cytoplasm. Next, cellular enzymes strip away the capsid so that the HIV genome is released. Also stripped away are proteins p24 and p17. Protein 24 coats the HIV genome and protein 17 lines the inside of the capsid.

The mechanism of host cell destruction remains under investigation, but three possibilities have been proposed:Viral budding tears a hole in the host cell's membrane, causing cytoplasmic leakage.The supply of useful T-lymphocytes is depleted, resulting from the formation of huge, functionless syncytia.Some mechanisms cause the provirus to provoke the synthesis of a large number of new HIV particles, causing the rapid depletion of cellular components and with it the destruction of the cell.

Examining the biopsy allows the structure of the marrow to be viewed as it exists in the body. It provides essential diagnostic information in conditions that disrupt the normal architecture, such as metastatic carcinoma, myelofibrosis, Hodgkin's lymphoma and granuloma. A biopsy may also be used to evaluate cellularity and identify acid-fast bacteria or fungi in less time than is needed for routine culture methods. One disadvantage of the tissue sections prepared from the biopsy sample is that morphologic detail is lost. For this reason, in many cases imprint slides or smears from the aspirated sample are also examined.

The components of the hematopoietic cords include: supporting cellsfat cellshematopoietic cellsarterioles

Another oil immersion field showing good cellular morphology.

This biopsy section was taken from a patient who has very few cellular elements in the marrow. Notice that over 90% of the marrow is composed of fat. If all of the cellular elements are decreased, the patient's condition is said to be pancytopenic or aplastic. There are numerous causes for aplasia, including drugs such as chloramphenicol, chemotherapy and inheritance (Fanconi's Anemia).

This low power view of a hematoxyln and eosin stained bone marrow biopsy shows fat cells as clear circles, and the darker intervening areas as blood cell precursors. This biopsy is about 25% cellular, or mildly hypocellular. A normal marrow in a middle aged adult is about 50% cellular.

It is possible that since anti-A and anti-B develop so predictably, without a recognizable immunizing event, that they are “naturally” occurring. Their production is thought to be stimulated by bacteria which have been shown to contain substances that are chemically similar to human A and B antigens. (Anti-A and anti-B are absent in germ-free animals.) Except for the rare hh individuals who lack H substance, everyone has some H in their cellular makeup.

Specialists in radioassay use radionuclides to determine the chemical makeup of body fluids such as blood and urine. Specialists in blood gas analysis evaluate lung and breathing function by levels of oxygen, carbon dioxide, pH, and hemoglobin with automated tests. Specialists in histology examine cellular and tissue samples using fixation, dehydration, embedding, microtomy, frozen sectioning, staining, and other similar techniques. Histology specialists licensed as technicians can perform specimen processing, embedding, cutting, staining, and frozen sectioning only under the general supervision of a director, supervisor, or technologist. Specialists in cytology process and interpret samples relating cytopathological disease. Non-gynecological cytology preparations can be screen by a specialist in cytology but final review and interpretation must be done by a physician.

Cellular immunity includes delayed hypersentivity reactions, graft rejection, graft-versus-host reactions, defense against intracellular organisms, and probably defense against neoplasms.Cellular immunity is mediated by lymphocytes which we call T-cells.T-cells are so named because they are dependent on the thymus for their production and development.The majority of T-cells are long-lived with an average lifespan of 4.4 years, but it is known that some survive for as long as 20 years or more.T-cells are capable of leaving and re-entering the circulation many times during their long life.T and B cells cannot be differentiated when viewing blood films.They are identified through the use of immunologic cell markers.

Antibody - A modified type of serum globulin synthesized by lymphoid tissue in response to antigenic stimulus. By virtue of specific combining sites each antibody reacts with only one antigen. Anucleate - Having no nucleus. Azurophilic granules - The well-defined large reddish granules (lysosomes) which may be present in large lymphocytes. They are called "azurophilic granules" because they stain blue with the azure stains which were originally used. Basophilic granules - Specific granules present in the cytoplasm of basophils. These granules are large and stain purple-black due to their strong affinity for basic stain. B-cell - Bone marrow derived lymphocytes which produce humoral antibodies. Biconcave - Having two concave surfaces. Cellular Immunity - The capacity of a small proportion of lymphoid population to exhibit response to a specific antigen. Chromomere - The centrally located granular portion of the platelet. Clone - A population of cells descended from a single cell. Delayed Hypersensitivity - (part of cellular immunity) that develops slowly over a period of 24-72 hours after an antigenic stimulus. It consists of an accumulation of cells around small vessels and/or nerves. Example: Tuberculin skin test reaction. Digestive Enzyme - A substance that catalyzes or accelerates the process of digestion. Eosinophilic Granules - Specific granules present in the cytoplasm of eosinophils. These granules are large, refractile spheres which stain reddish-orange due to their strong affinity for acid stain. Erythrocyte (red blood cell, RBC) - One of the elements found in peripheral blood. Normally the mature form is a non-nucleated, circular, biconcave disk adapted to transport respiratory gases. Fixed Macrophage - A phagocyte that is non-motile. Free Macrophage - An ameboid phagocyte present at the site of inflammation. Graft Rejection - A transplanted tissue that is rejected by the body's antibodies. Graft vs. Host Reaction - A complication that occurs when an implanted piece of tissue, which contains antibodies, rejects the host's tissue. Granulocyte - A leukocyte which contains granules in its cytoplasm, i.e., neutrophilic, eosinophilic, or basophilic granules. Half-life - is the length of time it takes for half of the cells circulating at a given time to leave the blood for the tissues. Hemocyte - Any blood cell or formed element of the blood. Hemostasis - A mechanism of the vascular system to arrest an escape of blood. It involves an interaction between blood vessels, platelets, and coagulation. Heparin - A mucopolysaccharide acid which, when present in sufficient amounts, functions as an anticoagulant by inhibiting thrombin. Histamine - A powerful dilator of capillaries and a stimulator of gastric secretions. Humoral Immunity - Acquired immunity produced after response to an antigenic stimulus in which B cells produce circulating antibodies. Hyalomere - the clear, blue non-granular zone surrounding the chromomere of a platelet. Immune Response - The interaction of a cell and an antigen that results in a proliferation of the cell and a capacity to produce antibodies. Isotonic Fluid - A fluid whose elements have an equal osmotic pressure. Leukocyte (white blood cell, WBC) - One of the formed elements of the blood; involved primarily with the body's defense. Lysosome - A microscopic body within cell cytoplasm; contains various enzymes, mainly hydrolytic, which are released upon injury to the cell. Megakaryocyte - A giant cell of the bone marrow from which platelets are derived. Mononuclear - A cell having a single nucleus.

Plasma and formed elements stay mixed in circulating blood. When centrifuged (or spun down), blood is separated into plasma, and formed elements including red blood cells. The plasma separator tube shown here has a barrier to maintain separation of plasma and cellular elements during centrifugation and storage. The red cell layer also includes a relatively small amount of platelets and white blood cells, not visible in the photo on the right.

Tubular filaments of fungi called hyphae may also be seen in a direct smear. Hyphae stain Gram positive and may branch or intertwine. Parasites can also be identified with the Gram stain, although it is not as sensitive as the special stains used for parasites. The Gram stain reaction and appearance can be used to identify most cellular material seen in a direct smear. The crystal violet may precipitate and can be seen on the slide. If the stain has precipitated, it must be refiltered before use.

Epithelial cells are larger than white blood cells and red blood cells, and contain a single nucleus. White blood cells (pus cells) usually show a segmented nucleus. Red blood cells are 1/2 to 2/3 as large as white blood cells, contain no nucleus, and are gram negative.Hyphae are gram positive tubular filamentous fungal elements which may show branching or intertwining. Yeast cells are round to oval, often budding, gram positive fungal elements, about the same size as RBCs. They are generally much larger than bacteria.

In addition to staining reaction and shape, it is important to observe the cellular arrangement of microorganisms on the smear. The cellular arrangements are:single cellspairschainsclustersbudding

The following information is reported:Gram stain reactionShapeThe cellular arrangement is not usually included in the report because it may vary, depending on the culture medium (liquid or solid) from which the organism was taken.

Another example of a target cell (or codocyte) is seen in the center of this slide. Notice that the hemoglobin in the center of this cell is somewhat lighter in appearance than in the previous slide. A second codocyte can be seen in the upper left portion of the slide. Codocytes appear in conditions which cause the surface of the red cell to increase disproportionately to its volume. This may result from a decrease in hemoglobin, as in iron deficiency anemia, or an increase in cell membrane. Target cells have excess membrane cholesterol and phospholipid and decreased cellular hemoglobin. Examples of other conditions in which target cells may be present include thalassemias, hgb C disease, post splenectomy and obstructive jaundice. Since their presence can be the result of an in vitro artifact, their value in clinical diagnosis is limited.

Microscopic examination of semen includes assessment of: sperm concentration percent motility percent viability cellular elements other than spermatozoa sperm morphology Sperm counting will be covered in this section. Assessment of other cellular components and of morphology will be covered in the next sections. For assessing count, motility, viability and other cellular components your laboratory will require a phase contrast microscope with 10x oculars and objectives up to 20x. For assessing morphology you will need bright field objectives up to 40x and 100x (oil immersion).

For assessing count, motility, viability and other cellular components your laboratory will require a microscope with 10x oculars and phase contrast objectives up to 20x. You will also need hand counters.For assessing morphology you will need bright field objectives of 40x and/or 100x (oil immersion).You will also need counting chambers, glass slides and coverslips and a method for staining sperm for morphology assessment.

Cellular casts consists of a Tamm-Horsfall mucoprotein matrix containing red or white blood cells, renal tubular epithelial cells, or a mixture of these cell types. All cellular casts originate from the distal tubules. The presence of cellular casts is always abnormal.

The most common type of cell seen in the urine sediment is the epithelial cell. This slide shows squamous epithelial cells under low power brightfield microscopy. They appear as large flattened cells with abundant cytoplasm and small round central nucleus. Although squamous epithelial cells have little clinical significance they must be differentiated from other cellular elements.

Chediak-Higashi syndrome is a rare autosomal recessive disorder. It results from a mutation of the gene LYST which encodes a protein with multiple phosphorylation sites. This defect causes a cellular abnormality involving the fusion of cytoplasmic granules. Early in neutrophil maturation normal azurophilic granules form, but they fuse together to form megagranules. Later during the myelocyte stage, normal specific granules form. The mature neutrophils contain both normal specific granules and abnormal azurophilic granules. These large abnormal granules can be seen in the cytoplasm of neutrophils, eosinophils, basophils, monocytes and lymphocytes. These abnormal granules are able to kill bacteria in neutrophils and monocytes; however, the process is much less effective than in normal cells in part, because these neutrophils have impaired locomotion. For these reasons, individuals with Chediak-Higashi have recurrent infections. An accelerated lymphoma-like phase occurs, with lymphadenopathy, hepatosplenomegaly, and pancytopenia. Death often occurs at an early age.

The Pelger-Huet anomaly is a congenitally acquired condition of nuclear segmentation and is clinically insignificant. There is no loss of cellular function.The condition can be suspected if typical bilobed, "pince-nez" nuclei are observed (left upper frame in the composite photograph).Band neutrophils usually have two distinct lobes, connected by a relatively short but thick bridge as illustrated in the upper and lower right frames. Monolobated cells may also be encountered, as illustrated in the lower left frame. If these are seen in significant numbers, the possibility of a homozygous Pelger-Huet should be considered.