Blood glucose (BG) homeostasis is a process that stabilizes BG levels in response to internal and external conditions, to maintain a normal range of 70 – 130 mg/dL (3.9 – 7.2 mmol/L).
Figure A displays the location of the lungs and airways in the body. Figure B shows a cross-section of a normal airway, while Figure C shows a cross-section of an airway during an asthma attack. An asthma attack is considered an acute condition because symptoms are severe and appear suddenly, requiring urgent or short-term care. However, once treated, symptoms typically ease or disappear.
On the lateral surface of the right half of the diaphragm, there is a calcified pleural plaque that developed after a history of significant asbestos exposure. Symptoms of asbestos poisoning, an insidious progressive condition, develop slowly and are not obvious at first. Pleural plaques, such as the one seen in the figure, can develop 20 or more years after initial asbestos exposure.
Figure A exhibits healthy lungs and airways in the body. Figure B shows lungs damaged by chronic obstructive pulmonary disease (COPD), with damaged bronchioles and alveolar walls. Chronic conditions like COPD, develop over an extended period of time and, as a result, typically have long-lasting effects.
Electron micrograph of red blood cells infected with Plasmodium falciparum, the parasite that causes malaria in humans. Patients with malaria often exhibit a relapse of symptoms following a peak of symptoms and, occasionally, long periods of dormancy.
Mary Mallon, nicknamed “Typhoid Mary”, was an asymptomatic carrier of Salmonella typhi, the pathogenic bacterium that causes typhoid fever. Due to her subclinical infection (an infection that caused few/no signs), she infamously infected over fifty people, leading to three confirmed deaths (New York American (1909)).
One of the signs exhibited during the prodromal stage of measles is the formation of “Koplik spots” on the mucosa of the cheeks and tongue (asymmetrical red spots with a white center).
Convalescence is the period following illness, injury, or surgery during which the body recovers and may require changes in lifestyle. During convalescence following a total knee replacement, patients are encouraged to walk to aid in the healing process.
Stylized rendering of the Human Immunodeficiency Virus (HIV). The late clinical stages of HIV infection develops into Acquired Immune Deficiency Syndrome (AIDS), a life-threatening condition that damages the immune system and makes the affected person extremely susceptible to certain conditions, infections, and cancers. Given the severity and contagiousness of AIDS, it became listed as a notifiable disease (a disease that requires health providers to report to public health officials) in Canada in 1982.
Predisposing factors, clinical manifestations, signs, and symptoms
The standard clinical manifestations of acute African trypanosomiasis include a “trypanid rash”, small pink-spotted rash on the abdomen.
The symptoms of COVID-19. The frequency of symptom appearance is in brackets for common and uncommon symptoms.
List common types of etiologies of diseases, disorders, and cellular damage:
Infectious agents (viruses, bacteria, fungi, protozoa, and helminths)
Infectious agents, pathogens that cause disease, include RNA and DNA viruses, bacteria (gram-positive and gram-negative), fungi, and protists.
Parasites are organisms that live in or on a host and use their host’s resources at the expense of the host. (credit: adapted work from NIAID)
Nutritional deficiencies
Hyperpigmentation of knuckles, along with other parts of the extremities, is characteristic of vitamin B12 deficiency.
Fluid/electrolyte imbalances
Symptoms of acidosis, a form of electrolyte imbalance where the body’s acid/base ratio is out of balance.
Exposure to toxins, radiation, alcohol, drugs, teratogens
A dynamic interplay between the amount of DNA damage and DNA damage response (DDR) upon exposure to IR determines the biological outcome in cellular and organismal contexts (Figure and caption obtained from Kabilan et al., 2020). Initial DNA lesions caused by exposure to IR are proportional to dose and trigger the DDR; a signaling cascade that senses damage and activates various DNA repair mechanisms, cell cycle arrest, if required, antioxidant defense and other relevant pathways. The magnitude of DDR and downstream branching to more specialized pathways (e.g., survival vs. apoptosis or homologous recombination [HR] vs. non-homologous end joining [NHEJ] DNA repair) may depend on various factors, such as dose, dose rate, radiation type and linear energy transfer, cell type and, microenvironment. Upon exposure to LDR, the DDR triggered is thought to not only repair the low amount of DNA damage caused, but also to render cells resistant to subsequent genotoxic stresses (a radioadaptive response). Such LDR-induced adaptation may last long enough to suppress the rates of mutation, genomic instability, senescence/aging and tumorigenesis caused by either HDR or endogenously generated reactive oxygen species, resulting in radiation hormesis. If, however, the degree of DNA damage produced by IR is high enough—typically above a certain threshold dose that may vary depending on cell type/organism—the capacity of the triggered DDR is insufficient to complete repair. This causes detrimental consequences, such as mutations, genomic instability, neoplastic transformation or tissue dysfunction. The interplay between the DDR and DNA damage is, therefore, dynamic and depends on a multitude of contextually determined factors.
Toxoplasma gondii tachyzoites, stained with Giemsa, from a smear of peritoneal fluid obtained from a mouse inoculated with T. gondii (Image by CDC). Tachyzoites are the asexual forms of T. gondii that rapidly divide and infect various cell types, including neural cells and renal cells. T. gondii is a parasite that is a well-known teratogen, causing toxoplasmosis. If pregnant women become infected with T. gondii, the parasite is able to cross the placental barrier, leading to severe congenital defects, such as blindness, deafness, and epilepsy.
Symptoms of lead poisoning, which include abdominal pain, constipation, headaches, irritability, memory problems, infertility, and tingling in the hands and feet, though can be more severe, causing seizures, coma, or death. Lead exposure can occur via contaminated air, water, dust, food, or commercial products.
Thalidomide is an oral medication that was marketed in the early 1950s as a treatment for morning sickness. United States Food and Drug Administration (U.S. F.D.A) medical officer Dr. Frances Kelsey refused to approve the 1960 application to market thalidomide in the U. S. for lack of adequate safety data. Soon, evidence began to appear worldwide linking this drug with grave birth defects.
Congenital malformation of the feet due to exposure to thalidomide, a potent teratogen, during pregnancy (photo provided by Otis Historical Archives National Museum of Health and Medicine). Thalidomide exposure during pregnancy leads to many severe birth defects, including phocomelia (abnormal limb development), and pre-mature death.
Mercury contamination is a problem in the Florida Everglades, and in many bodies of water throughout the world (Photo by Tom Friedel). In the Everglades, mercury is supplied via atmospheric deposition, groundwater discharge, and stormwater run-off. Mercury content in the water and fish are so high that swimming or fish consumption should be limited or completely abstained to avoid mercury toxicity.
Cutaneous mercury granuloma is a rare disorder caused by the introduction of elemental mercury (Hg) into skin (Photo by Y. Rosen). Metallic mercury in tissue appears as black, opaque, spherical globules of varying size. They provoke a granulomatous foreign-body reaction composed of foreign body giant cells, granulomas and a mixed inflammatory infiltrate. The method of introduction could be skin penetration by a mercury-containing object or the use of mercury-containing medication to treat an open wound.
United States Environmental Protection Agency (U.S. EPA) emergency response contractors clean up mercury at a Nevada home. Symptoms of mercury poisoning vary depending on exposure dose, duration, method, and type, though symptoms can include kidney and central nervous system damage, or death.
Cystic fibrosis is a genetic disorder that affects cells that produce mucus, sweat, and digestive juices. This results in severe damage to the lungs and digestive system, along with other organ systems in the body.
Sickle cell anemia is part of a group of genetic disorders known as sickle cell disease. In those with sickle cell anemia, red blood cells, which are usually round, flexible and flow easily within blood vessels, are sickle-shaped and lead to blockages to blood flow. This sickle shape is caused by an abnormal form of hemoglobin, a protein responsible for carrying oxygen. As a result, less oxygen is delivered to organs of the body, leading to severe consequences, including stroke.
A positive wrist sign in a patient with Marfan syndrome, where the thumb and little finger overlap when grasping the wrist of the opposite hand. Marfan syndrome is a genetic disorder that affects connective tissues (gives support, protection, and structure to other tissues and organs), commonly affecting the heart, eyes, blood vessels and skeleton. Individuals with Marfan syndrome are typically tall and thin, with unusually long arms, legs, and digits.
Spontaneous DNA mutations (e.g. most cancers)
Idiopathic
Iatrogenic
Congenital multifactorial defects (e.g. congenital heart defects, hypospadias, clubfoot (inward turn of foot), Down syndrome, cleft lip and cleft palate, limb defects, and at times mental dysfunction).
A: The structure and blood flow in the interior of a normal heart. The blue arrow shows the flow of oxygen-poor blood as it is pumped from the body into the right atrium and then to the right ventricle. From there, it pumps through the pulmonary artery to the lungs, where it picks up oxygen. The oxygen-rich blood, shown with a red arrow, flows from the lungs through the pulmonary veins into the left atrium B: Two common locations for a ventricular septal defect, a form of congenital heart defect. The defect, or hole, allows oxygen-rich blood from the left ventricle to mix with oxygen-poor blood in the right ventricle before the blood flows into the pulmonary artery. The mixed blood is shown with a purple arrow.
Hypospadias is a congenital malformation in males, characterized by abnormal fetal development of penis so that the opening of the urethra is located on the underside of the penis rather than the tip. In subcoronal hypospadias, the urethral opening is located just below the head of the penis. In midshaft hypospadias, the urethral opening is located halfway down the underside of the penis. In penoscrotal hypospadias, the urethral opening is located where the shaft of the penis meets the scrotum.
Clubfoot, which affects the muscles and bones in the feet, is the most common congenital malformation (occurs in about 0.1% of births). Affected feet (can be only one or both) twist down and rotate inwards.
A food abduction brace consists of two straight-border, high-top, open-toe shoes attached to an aluminum bar, with the heels of the shoes at shoulder distance apart and the shoes themselves set at 60-70 degree angles. This device is used as part of the Ponseti method (a series of casting and orthotic brace treatments) of non-surgically treating young children born with clubfoot.
An 8-year-old boy with Down Syndrome, a genetic disorder induced by the presence of a third copy of chromosome 21. Symptoms include developmental delays, mild to moderate intellectual disabilities, and characteristic physical features.
Karyotype (an individual’s complete set of chromosomes) of trisomy 21 (Down syndrome), where there is the presence of a third copy of chromosome 21.
Cleft lift and cleft palate are among the most common congenital defects, where parts of the upper lip or palate do not fuse properly in utero. Unilateral cleft lip and/or palates occur if the defect only occurs on one side, while bilateral cleft lip and/or palates occur when the defect is on both sides.
Newborn with radial aplasia (malformation of the radius bone) of the right arm. Children born with radial aplasia can either have a short or missing radius bone in one or both arms, with either a malformed or missing thumb. Radial aplasia is a congenital limb defect that is part of the condition VACTERL association (a group of birth defects that tend to be present at the same time).
Fragile X syndrome is an inherited disorder caused by a mutation (CGG nucleotide repeat) in the FMR1 gene. The disorder is characterized by learning disabilities, delayed development, and mental health problems.
Vascular ischemia of the toes with the characteristic cyanosis (bluish-purple hue to skin).
Cyanosis (bluish-purple hue of the skin) on the hand of someone with low oxygen saturation levels in their bodily tissues (hypoxia).
Electrical burn exit wound. Current flows through the body from the entrance point, until finally exiting where the body is closest to the ground. This foot suffered massive internal injuries, which weren’t readily visible, and had to be amputated a few days later.
Hives (raised, itchy welts) is skin reaction in response to the presence of an allergen. Allergies are a type of immune system disorder, where there is an overactive immune response to an otherwise harmless substance.
Pathophysiological mechanisms of autoimmune diseases. Autoimmune diseases are multifactorial diseases, and their etiologies are not yet fully known. Their development depends on genetic susceptibility, environmental factors, hormonal factors, and immune dysregulation. These factors may influence, according to different mechanisms, the abnormal activation of potentially dangerous autoreactive cells.
Autoimmune diseases, conditions that result in the immune system attacking its own tissues, can affect many organs in the body and have several factors that influence their onset.
Types of autoimmune diseases. There are two categories of autoimmune diseases: organ-specific autoimmune diseases and non-organ specific autoimmune diseases, also called systemic diseases. Organ-specific autoimmune diseases are restricted to certain organs or a particular tissue. Non-organ specific autoimmune diseases are characterized by extensive lesions that are secondary to an autoimmune reaction against ubiquitous autoantigens.
A butterfly rash, a red rash on the face that spreads on both cheeks on either side of the nose, is one of the most distinctive signs of lupus. Lupus is an autoimmune disease where the immune system attacks its own tissues.
Inflammatory bowel disease (IBD) is a group of inflammatory conditions that cause inflammation of the gastrointestinal tract. Ulcerative colitis and Crohn’s disease are the principle forms of IBD.
Hurler’s syndrome, a genetic disorder that results in abnormal bone structure and developmental delays, is caused by the absence of the enzyme alpha-L-iduronidase. This enzyme normally degrades glycosaminoglycans; however, in its absence, there is an accumulation of complex sugars in cells.
Tay-Sachs disease (TSD) is a progressive neurodegenerative disease caused by the absence of beta-hexosaminidase A, an enzyme that normally forms a complex that breaks down lipids (GM2 gangliosides) within lysosomes. One of the major signs of TSD is the “cherry red spot”, where the center of the fovea appears bright red against the fundus, which appears chalk-white. The disease progresses to other symptoms that include paralysis, seizures, and vision and hearing loss.
Neoplastic diseases (e.g. benign tumor or malignant tumor)
Kaposi’s sarcoma (KS) on the skin of an AIDS patient. KS is a disease where cancer cells develop in the skin or mucous membranes that line the gastrointestinal tract (from mouth to anus). The resulting malignant tumours appear purple or dark red, forming nodules that can spread to the lymph nodes or other organs.
Lipomas are slow-growing lumps made up of fatty tissue (benign tumours) that typically form just under the skin.
Endogenous/Exogenous intracellular accumulation due to:
abnormal metabolism (abnormal enzyme function) – occurs in fatty alcoholic liver disease, damaged/dysfunctional hepatocytes produce & accumulate too much lipid
Pathogenesis of alcoholic fatty liver disease, a metabolic condition that results in excess fat in the liver. Inc: increase, Dec: decrease, FA: fatty acid, Infl: inflammatory, TNF: tumor necrosis factor alpha.
abnormal protein preparation (e.g. abnormal protein folding or transport) – occurs in Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), amyotrophic lateral sclerosis (ALS) and prion diseases (Creutzfeldt-Jacob)
A normal brain is displayed on the left, while a Alzheimer’s diseased brain is on the right. In Alzheimer’s disease, misfolded proteins (beta-amyloid peptide and tau protein) aggregate to form extracellular amyloid plaques and intracellular neurofibrillary tangles (NFT). As a result, the brain shrinks significantly and brains cells die off, leading to difficulty recalling recent memories.
Parkinson’s disease (PD) is a progressive disorder that affects the nervous system, leading to issues with movement, mental health, sleep, and pain, among other health issues. In the late stages of PD, cognitive deterioration is characterized by the presence of Lewy bodies (abnormal aggregates of the protein alpha-synuclein) in the substantia nigra (region of the brain where dopamine is produced).
Huntington’s disease (HD) is an inherited neurodegenerative disorder where brain cells slowly lose function and then die. The disease occurs in part due to excessive repetitions of the cytosine-adenine-guanine (CAG) nucleotide sequence in the HD gene (bottom).
Amyotrophic lateral sclerosis (ALS) is a progressive fatal disease that causes degeneration of nerve cells in the spinal cord and brain. ALS affects the upper motor neurons (red), lower motor neurons (blue), and frontotemporal region of the brain, along with the associated muscles. As a result, the disease causes issues with voluntary control of the arms and legs, along with trouble breathing.
Micrograph showing spongiform degeneration (holes/vacuoles) in the cerebral cortex of a patient who had died of Creutzfeldt-Jakob disease; the scale bar = 30 microns (0.03 mm). Creutzfeldt-Jakob disease is a prion disease (a type of misfolded protein that causes other proteins to also fold abnormally) that causes behavioural changes, memory problems, poor coordination, and visual disturbances.
abnormal lysosome function – occurs in Lysosomal Storage Diseases (e.g. Gaucher Disease)
inability to degrade phagocytosed particles (e.g. coal dust, in pneumoconiosis)
Describe stages of drug discovery, placebo, double blind study, true positive, false positive, true negative, false negative, sensitive test, specific test, valid, reliable
List types of Diagnostic Tests: Genetic test, Urinalysis, Blood test, Pulmonary function test, Echocardiogram, Electrocardiogram, Electroencephalogram, Electromyogram, Imaging (X-ray, ultrasound, CT scan, MRI), Endoscopy, Histology
The procedure of urinalysis. Left: A urine test strip is immersed into the sample. Top right: A urine sample is about to be examined under a phase-contrast microscope using a Neubauer counting chamber. The urine is under the cover slide, in the upper segment formed by the H-shaped grooves. Bottom right: Phase-contrast microscopic image showing many white blood cells in the urine (pyuria).
A Blood test is a laboratory examination of blood. Blood tests are very common diagnostic tests for a variety of conditions, but are also used track general health and assess the effectiveness of current treatment/management of previously diagnosed conditions.
Spirometry is the most common type of pulmonary function test. he patient takes a deep breath and blows as hard as possible into a tube connected to a spirometer. The spirometer measures the amount of air breathed out. It also measures how fast the air was blown out.
Animation showing an echocardiogram. An echocardiogram is the visual image created via non-invasive ultrasonic examination of the heart to assess functionality and structure.
Electrocardiography (ECG/EKG) is a test that records the electrical activity of the heart. An ECG is used to assess the functionality and health of the heart, determine whether a heart attack occurred, or monitor a heart condition.
Schematic diagram of sinus rhythm for a human heart as seen on an electrocardiogram.
Electroencephalography (EEG) is a test that measures the electrical activity of the brain. Electrodes are attached to the scalp to record electrical impulses of brain cells.
Electromyography (EMG) is a test that measures the electrical activity of skeletal muscles. An EMG assesses the health of muscles and the nerve cells that control them.
Electromyography during gait termination (the transition from continuous walking to a complete stop). The resulting record (an electromyogram) displays the electrical activity of the muscles under examination.
X-ray technician collimating and correctly positioning a patient for a chest x-ray examination. An x-ray, a form of electromagnetic radiation, allows imaging of structures inside the body. They are mainly used to examine bones and joints, but may be used to examine soft tissue, such as internal organs.
A chest X-ray.
Ultrasound (also referred to as sonography or ultrasonogrpahy) is a noninvasive imaging test that uses high-frequency sound waves to visualize internal organs or other internal soft tissues.
A modern computed tomography (CT) scanner, a medical imaging device that allows for detailed imaging of internal body structures.
A computed tomography (CT) scan of a right temporal small punctate intracranial hemorrhage.
Magnetic resonance imaging (MRI) scanner, which uses magnetic forces and radio waves to create detailed three-dimensional images of internal bodily structures. A contrast medium, such as gadolinium-based contrast agents (GBCAs), may be used to enhance imaging.
An animated MRI image of the human head. Magnetic resonance imaging (MRI) is a test that uses magnetic forces and radiofrequency waves to create detailed three-dimensional images of internal structures in the body, including organs, bones, and tissues.
A hyperpolarized xenon (Xe) gas magnetic resonance image (MRI) facilitates detailed examination of the lungs to assess structure and function. The use of hyperpolarized Xe gas, which is inhaled by the patient prior to MRI scanning, enhances the MRI signal to allow for an intricate study of pulmonary function.
A nasal endoscopy. An endoscopy is a procedure that uses an endoscope to examine internal structures of the body.
An endoscope is a tool used in endoscopy to examine internal bodily structures. Endoscopes are typically thin, hollow tubes with a light on the end. However, endoscopes can be equipped with a small video camera so that the operator can project the video on a computer screen, for example during surgery.
A histology lab. Medical histology is the microscopic examination of tissues and organs. Samples are sectioned, stained, and viewed under the microscope.
Histological sample of basal cell carcinoma, showing tissue covered by squamous epithelium with a neoplasm arising from the basal layer.
Describe different types of Necrosis:
Liquefaction, Coagulative, Fat, Caseous
Liquefactive necrosis in the lung following angioinvasive aspergillosis, the most severe and aggressive form of invasive aspergillosis (caused by Aspergillus fungi infection). Liquefactive necrosis is a type of cell death characterized by a transformation of tissue into a liquid, viscous mass, which is often associated with microbial infections or internal chemical burns.
Histopathology (H&E stain) of acute myocardial infarction, showing coagulative necrosis of cardiomyocytes. Coagulative necrosis is a form of cell death that occurs when blood flow stops or slows (ischemia) to any type of cell in the body (except for the brain).
High magnification micrograph of fat necrosis, a type of cell death that only occurs in adipose cells and is caused by some form of physical trauma that results in injury/loss of blood supply (ex. surgery). Hard lumps may form under the skin where fat necrosis occurs, though this can disappear over time.
Caseous necrosis enclosed within a granuloma in the lung during the late stages of tuberculosis following infection by Mycobacterium. Caseous necrosis is a type of cell death where tissue structure is destroyed and is characterized by its “cheesy” appearance.
Describe the difference between necrosis and apoptosis
Apoptosis consists of regulated cell death that does not result in inflammation, while necrosis is unregulated cell death that results in an uncontrolled release of inflammatory agents, causing inflammation.
Dystrophic and Metastatic Calcification, Infarction, Gangrene
Histopathology of dystrophic calcium phosphate microcalcifications in ductal carcinoma in situ (DCIS) of the breast, stained with hematoxylin and eosin (H&E) stain. Dystrophic calcification is calcification that occurs only in necrotic tissues and presents without elevated blood calcium levels.
Density-dependent colour scanning electron micrograph (DDC-SEM) of cardiovascular calcification showing spherical calcified particles in orange and soft tissue in green. Elevated serum levels of calcium leading to deposits of calcium salts in otherwise normal tissue is referred to as metastatic calcification.
Cross-section of the heart, showing an old myocardial infarction (obstruction of blood supply to the area, resulting in local tissue death) of the posterior wall of the left ventricle (pale areas). The right ventricle is seen at right.
Gangrene in the right foot in a person with diabetes. Gangrene is the death of tissue due to lack of blood flow or following serious bacterial infection, resulting in tissue break down and a greenish-black colour.
List factors that may at times pre-dispose to certain ailments:
A variant of the original map drawn by Dr. John Snow (1813-1858), a British physician who is one of the founders of medical epidemiology, showing cases of cholera in the London epidemics of 1854, clustered around the locations of water pumps.
Worldwide prevalence of hepatitis D virus (HDV) among hepatitis B virus (HBV) carriers in 2015. Eight genotypes have been identified worldwide by comparative phylogenetic analysis. Genotype 1 is the most frequent and has variable pathogenicity, Genotypes 2 and 4 are found in East Asia causing relatively mild disease. Genotype 3 is found in South America in association with severe hepatitis. Genotypes 5, 6, 7, 8 have been found only in Africa.Proactive control measures, such as social distancing or mask-wearing, can reduce peak number of cases during epidemics
Define biopsy
Human liver biopsy
Describe common cellular adaptations and understand why each occurs.
High magnification micrograph showing squamous metaplasia uncovered during a Pap smear. Metaplasia is the phenomenon where one cell type transforms into another. Squamous metaplasia describes the noncancerous changes in epithelial cells that line glands, organs, and skin.
High magnification micrograph displaying nodular histiocytic/mesothelial hyperplasia (NHMH). Hyperplasia is the increased proliferation of cells in normal tissue or organs, which may a precancerous condition. NHMH is characterized by the nodular-patterned proliferation of histiocytes and mesothelial cells.
High magnification micrograph of fibrous dysplasia. Dysplasia refers to the presence of abnormal cells within a tissue or organ of the body. Fibrous dysplasia refers to the condition where abnormal fibrous tissue is present in bone, weaking it.
Malignant neoplasm (tumour) showing marked anaplasia (cells vary in size and shape).
Micrograph of high-grade prostatic intraepithelial neoplasia (PIN). Neoplasia is the abnormal, uncontrolled growth of cells or tissues of the body, which can be benign or malignant. PIN specifically is the growth (noncancerous) of cells lining the internal and external surfaces of the prostate gland.
Diagram showing two tumours: the upper tumour is benign, meaning that it will stay at it’s point of origin and will not spread or invade other parts of the body. Benign tumours usually have distinct borders and have a slow growth rate. The lower picture depicts a malignant tumour, which is irregularly shaped, vascular, and may spread throughout the body via blood or the lymphatic system. Malignant tumours typically grow quickly and can become life threatening.
Malignant peripheral nerve sheath tumor (MPNST) on the back of a 65-year-old male. MPNST is a rare and aggressive cancer that develops in nerve sheaths. Malignant cancer cells are likely to spread from its original point of development in the body.
Immunohistochemistry of ductal carcinoma in situ (DCIS) with necrosis. Carcinoma in situ is a condition where abnormal cells group together only where they are first formed. These abnormal cells are not cancerous, but may become cancerous over time and spread throughout the body.
Micrograph of small cell carcinoma of the lung, also called small cell lung cancer. Carcinoma is cancer that forms in epithelial tissues that lines organs, and both internal and external body surfaces.
The process of metastasis. Once metastatic cells are attached to the basement membrane (a physical barrier that seperates tissue components), they break through with the help of an enzyme called type IV collagenase. Cancer cells then move through the blood stream enabling them to spread to other parts of the body. A secondary tumor may form at another site in the body.
A 3D rendering of a transmission electron micrograph of the human papillomavirus (HPV) capsid (pink) and HPV virus particles (green) harvested and purified from cell culture supernatant. HPV is a type of human oncovirus, a virus that causes cancer. Rendering by NIH 3D (3d.nih.gov/); Credit: NIAID.
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