Medical Application Of Histology .pdf

Clinical Correlation Histology Mitochondria : Muscle weakness (Mitochondrial myopathy), particularly affecting the...

Clinical Correlation Histology Mitochondria : Muscle weakness (Mitochondrial myopathy), particularly affecting the extra ocular muscles. Lysosomal storage disorders Degenerative disease of the central nervous system (e.g. loss of the optic nerve fibers, loss of *Genetic defects in the production of specific lysosomal acid hydrolases lead to an inability to cerebellar tissue or degeneration of brain white matter). degrade specific classes of molecule, which then accumulate in the acid vesicle system. Metabolic disturbances, by accumulation of high levels of lactic acid. *Most of these defects are inherited as single gene autosomal recessive traits. Such diseases is maternally inherited and may manifest at any age from childhood into adult life. Examples: * 1.Lysosomal glycogen storage disease (acid maltase deficiency) leads to the accumulation of MELAS: characterized by mitochondrial encephalomyopathy, lactic acidosis, recurring stroke- glycogen, which like episodes cannot be broken down. Other findings include 2.Tay–Sachs disease results from a deficiency in an enzyme degrading one of the sphingolipids Muscle weakness (hexosaminidase- Tonic-clonic seizures A deficiency). MERRF: characterized by myoclonic epilepsy with ragged red fibers destruction of 3.Huge amounts of lipid accumulate in lysosomes and lead to severe neuronal degeneration. important proteins involved in oxidative phosphorylation Other findings include Generalized seizures Smooth ER.. physiological jaundice in newborn is caused by immaturity of sER of liver cells that unable to conjugate the bile. Protensomes Alzheimer’s disease and Huntington’s disease are two neurologic disorders caused by accumulation of protein inside the cells due to failure of degradation by proteasomes. Peroxisomes Microtubules *A large number of disorders arise from defective peroxisomal proteins, because this Several inhibitory compounds used by cell biologists to study details of microtubule dynamics are organelle is involved in several metabolic pathways. also widely used in cancer chemotherapy to block activity of the mitotic spindle in rapidly *Probably the most common peroxisomal disorder is X-chromosome-linked growing neoplastic cells. adrenoleukodystrophy, caused by a defective integral membrane protein that participates in transporting very long-chain fatty acids into the peroxisome for Beta oxidation. Such drugs include vinblastine, vincristine, and paclitaxel, all of which were originally *Accumulation of these fatty acids in body fluids destroys the myelin sheaths in nerve discovered as plant derivatives. tissue, causing severe neurologic symptoms. The presence of a specific type of intermediate filament in tumors can often reveal the cellular origin of the tumor, information important for diagnosis and treatment of the cancer. Cillia Identification of intermediate filament proteins by means of immunocytochemical methods is a *Several mutations have been described in the proteins of the cilia & flagella. They routine procedure. One example is the use of GFAP to identify astrocytomas, the most common are responsible for the Kartagener or immotile cilia syndrome. type of brain tumor. *The symptoms are immotile spermatozoa, male infertility, & chronic respiratory infections caused by the lack of the cleansing action of cilia in the respiratory tract. cell Inclusion (Pigments) A condition termed hemosiderosis, in which the iron containing inclusion hemosiderin occurs in cells of organs throughout the body, may be seen with increased uptake of dietary iron, impaired iron utilization, or with excessive lysis of red blood cells. Hemosiderosis itself does not damage cell or organ function. However, extreme accumulations of iron in cellular hemosiderin can lead to disorders such as hemochromatosis and iron overload syndrome, in which tissues of the liver and other organs are damaged.  Neurons 1 I Parkinson disease Huntington chorea Parkinson disease is a progressive degenerative disease characterized by tremors, muscular Huntington chorea is a hereditary disease that becomes evident during the third decades of life, rigidity, difficulty in initiating movements, slow voluntary movement, and masklike facial expression. first presenting as painful joints and progressing to uncontrolled movement of joints, motor The cause is the loss of dopaminergic neurons from the substantia nigra of the brain. disfunction, dementia, and death. The cause is the loss of basal ganglia neurons that produce the neurotransmitter λ- aminobutyric acid (GABA). Guillain–Barré syndrome Multiple sclerosis (MS) *Autoimmune syndrome of the PNS is proceeded by bacterial or viral infection. & leading to *MS is a chronic inflammatory disease of the CNS characterized by a loss of myelin; immune destruction of Schwann cells and Schwann cell mediated myelin--------- results damaged patches called plaques appear in different areas of the white matter (central). in demyelination & axonal degeneration that affects the peripheral nerve roots. *The disease course is unpredictable and the type and severity of symptoms can vary greatly. *The first symptoms of Guillain–Barré syndrome are numbness, tingling, and pain, alone or in *During periods of MS activity, leukocytes (T cells) are drawn to regions of the white matter, combination. This is followed by weakness of the legs and arms that affects both sides equally which initiates an inflammatory response accompanied by loss of oligodendrocytes and and worsens over time. axon demyelination. Alzheimer Disease Alzheimer disease, a common type of dementia in the elderly, affects perikaryon and synapse within the cerebrum through formation of: 1- Neurofibrillary tangles, which are accumulations of tau protein and microtubules. 2. Neurotic plaques, which are dense aggregates of β-amyloid protein. -Neurons 2 => Ependymal Cells In multiple sclerosis, the myelin sheath is damaged by an autoimmune mechanism with *A decrease in the absorption of CSF or a blockage of outflow from the ventricles during various neurologic consequences. fetal or postnatal development results in the condition known as hydrocephalus (Gr. *In this disease, microglia phagocytose and degrade myelin debris by receptor-mediated hydro, water, + kephale, head), which promotes a progressive enlargement of the head phagocytosis and lysosomal activity. followed by mental impairment. In addition, AIDS dementia complex is caused by HIV-1 infection of the central nervous system. Overwhelming experimental evidence indicates that microglia are infected by HIV-1. A number of cytokines, such as interleukin-1 and tumor necrosis factor- activate and enhance HIV replication in microglia. Bladder Metaplasia: The bladder is normally lined by transitional epithelium. Chronic irritation Metaplasia: Under certain abnormal conditions, one type of epithelial tissue may transform of the bladder wall (e.g., from Schistosoma infection, urinary calculi, or indwelling catheters) into another type. e.g. in heavy cigarette smokers, the respiratory epithelium lining bronchi can result in a transformation of transitional to squamous epithelium. can be transformed to stratified squamous epithelium. Barrett esophagus: In cases of chronic acid reflux (regurgitation)from the stomach into the lower oesophagus, the stratified squamous non-keratinized epithelium of esophagus is replaced by a glandular mucus-secreting epithelium like that found in the stomach. This helps protect the esophagus against the injurious effects of the acid and pepsin but is also a Epithelial cell tumours occur when cells fail to respond to normal growth well-known precursor of oesophageal adenocarcinoma. regulatory mechanisms. 1. These tumours are benign when they remain local. 2. The malignant tumours can migrate to other organs (metastasis). Carcinomas are malignant tumours that arise from surface epithelia. Adenocarcinomas are malignant tumours that arise from glandular epithelium. - *Several mutations have been described in the proteins of the cilia & flagella. They are Celiac disease, also called gluten-sensitive enteropathy or sprue, is a disorder of the small responsible for the Kartagener or immotile cilia syndrome (Primary ciliary dyskinesia). intestine in which one of the first pathologic changes is loss of the microvilli (brush border) of *It is rare autosomal recessive disorder characterized by absent or dysmotile cilia caused by a the absorptive cells (enterocytes). defect in the microtubules (dynein arm mutations). This is caused by an immune reaction against the wheat protein gluten during *The symptoms are immotile spermatozoa, male infertility, & chronic respiratory infections its digestion, which produces diffuse enteritis that leading to malabsorption, caused by the lack of the cleansing action of cilia in the respiratory tract. and eventually to pathologic changes in the intestinal wall. N.B. Abnormal cilia also present in the polycystic kidney disorder The malabsorption problems and structural changes are reversible when gluten is removed from the diet. Junctional complex; is a several types of junction between adjacent epithelial cells - The enterotoxin secreted by Clostridium bacteria, which causes “food poisoning,” binds in order to maintain their structural and functional integrity. claudine molecules of intestinal cells, leading to disruption of tight junctions that causes loss of interstitial fluid through the intestinal lumen (diarrhoea) and intestinal ulcers. Pemphigus - Helicobacter pylori, one of the important cause of gastric ulcers, binds the extracellular Autoimmune disease characterized by production of antibodies against the desmosomal domains of tight-junction proteins in cells of the stomach leading to loss of the integrate of this proteins of the epidermal cells. tight junction. Affected people develop widespread skin and mucous membrane blistering. - Mutations in various connexin genes have been linked to certain types of deafness and peripheral neuropathy.