Introduction to

Pathology

What is pathology

Pathology is the scientific study of disease. In its

broadest sense, it is the study of how the organs

and tissues of a healthy body change to those of

sick person.

The four aspects of a disease process that

form the core of pathology

●Etiology

● Pathogenesis

● Pathological change

● Clinical pathological correlation and Prognosis

The scope of pathology

Etiology: causes of the disease

Pathogenesis: the mechanisms of its development

Pathologic changes: the structural alteration

induced in the cells and organs of the body.

Clinical pathological correlation and Prognosis :

the Clinical effects of the pathological changes.

Position

(1) Pathology is a bridging between basic science

and clinical medicine

(2) Pathology is also a practical clinic medicine

( Diagnostic Pathology or Surgical Pathology)

Classification

(1) Human pathology The principal aim of human pathology considers structural abnormalities of cells and tissues grossly and microscopically examined from patient’s tissues (2) Experimental pathologyExperimental pathology researches cellular processes incorporate animal experiment and tissue and cell cultures

1. Human pathology

(1) Autopsy (means

“see for yourself”)

Autopsy is a special

operation , performed

by specially trained

physician, on a dead

body

The functions of Autopsy

● Clarify the causes of death

● Diagnosis and treatment quality control

● Recognizing of negligence

● Recognition of new diseases and new diseases patterns

● Source of information

● Provide material for education

● material for scientific research

● Recognition of treatment effectiveness

Biopsy is the removal of a sample of tissue from the body for examination and the tissue will be examined under a microscope to assist in diagnosis

(2) Biopsy

(3) Cytology

Cytology is responsible for preparation, staining and microscopic examination. (smear, fine needle aspiration)

2. Experimental pathology

(1) Animal experiment: Animal experiment is a pathological method using animal model to study diseases within the body.

(2) Tissue and cell culture

Tissue and cell culture is that the tissue or cell

sample from a human or animal is obtained and

maintained in vitro for experimental, diagnostic

or therapeutic purposes

Basic examination methods

(1) Gross appearanceThe morphological feature of a lesion (such as size, shape, weight, color, consistency, surface edge, section) is observed by eyes or assisted by using a ruler, steelyard, magnifying glass, or other tools.

Lung cancer

(2) Histologic and cytologic observation

The specimens from patients are prepared as a

section or smear, then stained and examined by

using microcopy

cytologic observationHistologic observation

most common: basic formalin fixed → HE

(hematoxylin and eosin) stained

（ 3 ） Histochemistry and cytochemistry

Histochemistry and cytochemistry is also

called special stain method. Some tissue

structures and substances (protein, enzyme,

nucleic acid, glycogen, lipid) are colored when

a chemical group ( carboxyl, phosphoric, or

aldehyde) reacts with the stain

PAS (glycogen) →BM Sudan Ⅲ →fat

Immunohistochemistry

● Ag-Ab specific reaction

● Applications

Location analysis ( cytokeratin→cell membrane)

Clinical diagnosis and distinguishing (diagnosis of tumor histogenesis)

(4) others

Leiomyosarcoma Actin (+)

Electron microscope

Filtering membraneTEM (transmitting electron microscope)

Podocyte SEM (scanning electron microscope)

Flow cytometry (FCM)

● One kind of cells→quantitative analysis

● DNA ploidy analysis

● Protein and nucleus acid → quantitative

analysis

● Selection of collection of cells

application

Nuclei: diameter; circumference; area;volume; morphology

Image analysis (IA)

Laser scanning confocal microscope (LSCM)

aliving cell

observation in

situ or

development

or quantitative

Molecular biology technique

● Polymerase chain reaction (PCR)

● DNA sequencing

● Biochip technique

Gene chip (DNA chip)

Protein chip (protein microarray)

Tissue chip (tissue microarray)

Polymerase chain reaction (PCR)

History of Pathology

Autopsy → Organ pathology (1761)

LM → Cellular pathology (1854)

Ultrastructural pathology with the application of

EM (20 century 60s)

Immunopathology, Molecular pathology,

Genetic pathology, Quantitative pathology

Text of Pathology

(1) General pathology:

concerned with the basic reaction of

cells and tissues to abnormal stimuli

that underlie all diseases.

(2) Systemic pathology :

dedcribe the specific responses of specialized

organs and tissues to defined stimuli.