1. Histopathology Khamael Al-Abrahemi

2. Introduction of Histopathology Histopathology The study of the anatomical,chemical, and physiological alterations in an organ as organ as the result of diseases. Pathology is subdivided in to several fields. 1-General pathology 2- Special pathology 3- Experimental pathology 4- post –mortem pathology(Morbid anatomy) 5- Microscopic pathology (cellular pathology or photo pathology) 6- Ultra structure pathology 7-physiology pathology 8- chemical pathology 9- Macroscopic or gross pathology 10- clinical pathology 11- Necropsy,post –mortem examination or, autopsy. Necropsy= for animal Autopsy= for Human

3. What is the disease? It is the "State in which an individual exhibits an anatomical,physiological or biochemical deviation from the normal" Disease may be defined as:- An abnormal alteration of structure or function in any part of the body. Classification of diseases:- 1-Developmental- genetic, congenital. 2-Acquired 3- Inflammatory – Trauma, infections. 4- Neoplastic – tumers cancer 5- Degeneration – ageing 6- Metabolic 7- Iatrogenic : Drug induced.

4. The scope of pathology 1- the core of pathology:- the four aspects of a disease process that process that form the core of pathology :- 1- Etiology :causes of the disease 2- pathogenesis : the mechanisms of its development 3- Morphologic changes :- the structural alteration induced in the cells and organs of the body. 4- Clinical significance: the functional consequences of morphologic changes. Branches of pathology :- 1- General pathology 2- systematic pathology 3- Gross pathology 4- cellular pathology 5- Surgical pathology 6- clinical pathology 7- Immune pathology

5. Techniques of pathology 1-Human pathology a- Autopsy :- forensic pathology b- Biobsy :- surgical or diagnostic pathology 3- cytology: smear, fine needle aspiration. 2- Experimental pathology a Animal experiment : animal model b- tissue and cell culture. Etiology What is the cause? 1- Environmental agents 2-physical 3- chemical 4- Nutritional 5- Infection 6- Immunological7- psychological. Morphological :-structural changes Tumer in acancer, ulcer in an infection, Atrophy in dementia.

6. Observation and new technique of morphology Size,shape, weightm color,consistency, surface, edge, section. Stain used in pathology 1-Haematoxylin and eosin stain :-Haematoxylin affinity for nuclear chromatin blue discoloration while eosin for protein in cytoplasm pink discoloration. 2-periodic acid shift (PAS) glycogen, basement membrane, fungi, parasites 3- stain for micro organisms : Gram stain and zeihl – nelson stain. 4- Amyloid stain : congo red a myloid 5- Reticulin stain …… reticular fiber( type 111collagen in the connective tissue ) and basment membrane (type 1v collagen and lamina) used in tumer pathology 6- Giemasa stain…. Lymph or reticular elements.

7. Cellular Responses to stress and Harmful Stimuli Cells are continuously adjusting their structure and function and function to accommodate changing demands and extra – cellular stresses. This is referred to as homeostasis. should the cells encounter physiological or pathologic stresses or stimuli they can modify the homeostatic state and achieve anew steady state to counteract the noxious effects of these external stresses and stimuli. These changes are referred to as adaptations. the aim of these adaptations is to avoid cell injury &cell death. the injury may be reversible i.e. the cells return to normal state on the removal of the offending agent or irreversible i.e. there is no possibility of return to normal. Irreversible injury ultimately leads to cell death.

8. Cellular Adaptation Adaptations are reversible changes and are divided into 1-physiological adaptations :- usually represent responses of cells to normal stimulations e.g the hormone – induced enlargement of the breast and uterus during pregnancy. 2- pathological adaptations :- response to stress that allow cells to modulate their structure and function and thus escape injury. can take several distinct forms.. Type of adaptations include 1-Hypertrophy:- refers to an increase in the size of cells resulting in increase in the size of the relevant organ. Hypertrophy can be physiological or pathological and is caused either by increase functional demand or by specific hormonal stimulation. Example of physiological hypertrophy include that of skeletal muscle in athletes and

9. mechanical workers &the massive physiological enlargement of the uterus during pregnancy due to estrogen – stimulation smooth muscle hypertrophy (and hyperplasia). Example of pathological hypertrophy cardio megaly secondary to hypertension. B- hyperplasia :- refers to increase in the number of cells. It takes place only if the cell population is capable of replication it may occur with hypertrophy and often in response to the same stimuli. two type of physiological hyperplasia are 1- hormonal hyperplasia, example is proliferation of granular epithelia of the female breast at puberty and during pregnancy.

10. 2-compensatory hyperplasia, which occure when apportion of the tissue is removed or disease.most forms of pathological hyperplasia are caused by excessive hormonal or growth facter stimulation. For example,if there is persistent or excessive estrogen stimulation of the endometrium. C- Atrophy :- refers to shrinkage in the size of the cell by the loss of cell substance. this situation is exactly opposite to hypertrophy. when sufficient number of cells are invoved, the entric tissue or organ diminishes in size i.e becomes atrophic.

11. Causes of atrophy include:- a- Decrease workload (e.g immobilization of limb) b- decrease blood supply to limb c- Ina- dequate nutrition as in starvation. E- loss of endocrine stimulation as in post menopausal endometrial atrophy F-Aging D- Metaplasia :- reversible change in which one which one adult (mature) cell type (epithelial or mesenchymal) is replaced by another adult cell type.E.g epithelial metaplasia is the squmaous change that occure in the respiratory epithelium in cigarette smokers. the normal ciliated columnar epithelia cells of the trachea and bronchi are focally or widely replaced by stratified by squamous epithelial cells.