Lecture 1: Introduction + Cell Adaptation PDF

BIOM444 Histopathology Lecture 1: Cell Adaptation Dr. Amal Al-Haidose Course Information • • • • • • • Course Name: BIOM444 Histopathology Pre-request: Histology + Introduction to Pathology Level: Undergraduate Time: Tuesday 9:00- 9:50 Credit Hours: 2 Room No: Lecture: I06- Pharmacy Building F.CL...

BIOM444 Histopathology Lecture 1: Cell Adaptation Dr. Amal Al-Haidose Course Information • • • • • • • Course Name: BIOM444 Histopathology Pre-request: Histology + Introduction to Pathology Level: Undergraduate Time: Tuesday 9:00- 9:50 Credit Hours: 2 Room No: Lecture: I06- Pharmacy Building F.CL.06 Lab: HMC/Sidra/QU (TBA) Tuesday 12:00-2:50 Course Assessment Assessment Theory Mid-term Exam 30% Practical Exam 15% Lab Reports Poster Oral presentation Final Exam 5% 5% 5% 40% Histopathology • Learning Resources: • Textbooks: What is Histopathology? Greek word Histo- tissue Pathos- disease suffering • The study of abnormal or diseased tissue and organs using microscope. • Histopathology = anatomical pathology = Pathology Methods Of Studying Histopathology • Light Microscopy- the structure of tissues & cells in health & disease • Immunohistochemistry- employ antibodies (immunoglobulins with antigen specificity) to visualize substances in tissues sections • Electron Microscopy- study of disorders at an organelle level & to the demonstration of viruses in tissue samples 6 Biopsy • Tissues for histopathological examination are obtained by biopsy. • Biopsy is a surgical procedure to obtain tissue from a living organism for its microscopical examination, usually to perform a diagnosis. • Biopsy can be either incisional or excisional. 7 Type of biopsy used in diagnostic histopathology • An incisional biopsy is a procedure in which a small area (sample) of tissue is taken to identify the composition (or make-up) of a lesion or abnormality • e.g: Biopsy of skin rash • An excisional biopsy is essentially the same as incisional biopsy, except the entire lesion or tumor is removed. • e.g: Benign breast lump 8 Liver Biopsy Colon Biopsy Esophagus Biopsy Endometrial Biopsy Endometrial suction catheter Autopsy • Also known as a post-mortem examination or necropsy • The examination of a dead body to determine the cause of death and to evaluate any disease or injury that may be present. • Autopsies are either performed for legal or medical purposes. • A forensic autopsy is carried out when the cause of death may be a criminal matter • Clinical or academic autopsy is performed to find the medical cause of death and is used in cases of unknown or uncertain death, or for research purposes. Lecture 1 14 Overview Cells must adapt to, an environment which is continually changing; in temperature, dehydration, nutrition… If the stimulus is overwhelming, the cells undergo degeneration or cell death. However, many stimuli cause cells to adapt by altering their pattern of growth 15 Overview Stress, demand ADAPTATION Fails to adapt NORMAL CELL (Homeostasis) Injurious stress CELL INJURY CELL DEATH 16 Cellular Adaptation to Stress 1. Atrophy 2. Hypertrophy 3. Hyperplasia 4. Metaplasia 5. Dysplasia 17 Atrophy • Definition: Shrinkage of cells • Classified as: Physiologic- due to aging or decreased work load (e.g., decreased size of uterus following child birth) Pathologic- primarily due to denervation of muscle, diminished blood supply, nutritional deficiency, Loss of hormone stimuli Example of Atrophy I’m Normal ! Atrophy Attack!:???? 19 Hypertrophy • Definition: increase in cell size • No increase of cell number • An increase in the size of parenchymal cells and consequently an increase in the size of the organ. Hypertrophy • Mechanical stimuli: skeletal muscle of a sportsman • Increased workload: left ventricle hypertrophy of systemic hypertension • In paired organs as in kidney: when one kidney is absent or removed surgically, the other kidney is enlarged in size. Hypertrophy Hypertrophy of the left ventricle Normal myocardial fibers Hypertrophic myocardial fibers Hypertrophy • Endocrine hypertrophy • Hormonal stimuli: pregnant uterus • Excessive growth hormone leads to gigantism or acromegaly Hyperplasia • Definition: Increase the number of cells in an organ or tissue. (increase rate of cellular division) • Hyperplasia can be divided into: – Physiologic hyperplasia • Hormonal: Breast glandular epithelium at puberty & pregnancy – Compensatory hyperplasia • liver after partial resection – Pathologic hyperplasia Compensatory Hyperplasia • Regeneration of liver following partial hepatectomy. • Erythroid hyperplasia of bone marrow in chronic hypoxia (mountain climbers). 25 Pathologic Hyperplasia a)Excessive hormonal or growth factor stimulation • Thyroid gland: due to increased thyroid stimulating hormone (TSH) in thyrotoxicosis •Endometrial hyperplasia: due to estrogen excess b) Hyperplasia is an important response of CT cells in wound healing. Growth factors are produced by WBCs responding to injury & by cells in ECM. Hyperplasia Hyperplasia (a) Normal proliferative phase endometrium (HP) (b) Hyperplasia of endometrium (HP). Endometrial hyperplasia occurs when there is abnormal oestrogenic stimulation. Micrograph (a) shows normal proliferative-phase endometrium responding to normal ovarian oestrogenic stimulation. In contrast, in micrograph (b), the endometrial glands are markedly hyperplastic, and continued increase in the number of cells in each gland has resulted in some glands G showing cystic dilatation. Pathologic Hyperplasia c) Hyperplasia due to viral infection. HPV that causes skin warts. Growth factors may be produced by virus or by infected cells. Hypertrophy + Hyperplasia The massive physiologic enlargement of the uterus during pregnancy occurs as a consequence of estrogen-stimulated smooth muscle hypertrophy and smooth muscle hyperplasia. Hyperplasia & CANCER Pathologic hyperplasia constitutes a fertile soil in which cancerous proliferation may eventually arise. • Endometrial hyperplasia: increased risk of endometrial cancer • Certain HPV infections: predisposes to cervical cancers Metaplasia • Definition: change in cell type • A reversible change in which one mature cell type is replaced by another mature differentiated cell type. • The significances of metaplasia are to withstand with an environmental change (usually pathological). Transformed or cancerous cell Metaplasia of the Bronchus Columnar respiratory epithelium cell of the bronchi may replaced by squamous epithelium under the influence of cigarette smoke (squamous metaplasia). Barrett Metaplasia Metaplasia from stratified squamous epithelium to columnar: Barrett metaplasia in lower part of esophagus Dysplasia • Not a true cellular adaptation • Dysplasia is usually judged on the basis of changes in cell nuclei: • irregularity of the nuclear envelope and of chromatin distribution • changes in the ratio of nuclear area to cytoplasmic area, and abnormalities in epithelial maturation. • Loss of the normal cell architectural orientation and uniformity of the individual cells. • Strongly associated with common neoplastic growth 34 Dysplasia: The normal squamous epithelium at the left transforms to a disorderly growth pattern at the right. Summary of Cellular Adaptation to Stress Malignant tumor Dysplasia Metaplasia Normal cells Adaptation Atrophy Hyperplasia Hypertrophy