Intro to Histology

Question 1

Define and explain the relevance of a knowledge of histology and cytology to the practice of osteopathic medicine

Answer 1

Structure and function are reciprocal – be able to define normal structure and abnormal structure can lead to associated functions
May need to look at pap smears, fluid samples, or biopsies

Question 2

Describe the general approach to the preparation of human tissues and cells for routine histologic evaluation in patient care

Answer 2

1) FIX the enzymatic activity/tissues
2) Parafin EMBEDDING and slicing
3) PROCESSING: dissolve parafin, hydrate, stain, dehydrate

Question 3

Explain the importance of a three-dimensional perspective of microscopic tissue sections and an understanding of typical “artifacts” seen in the histopathologic evaluation of patient specimens

Answer 3

Tissue sections can demonstrate varying 2-D views of a cell and we need to be aware that we are only viewing a small piece
artifacts: changes due to histological preparation (i.e. spaces between cells)

Question 4

4 basic types of tissues

Answer 4

muscle
connective
epithelial
nerve

Question 5

Define histogenesis and outline the tissues derived from each of the three germ cell layers

Answer 5

histogenesis: knowing the layers in which cells and tissues derived from (embryogenesis)
Ectoderm (outer)
Mesoderm (middle)
Endoderm (inner)

Question 6

Explain enzyme histochemistry

Answer 6

allows you to stain structures not able to be stained using H&E staining (such as PAS with glycogen)

Question 7

Explain direct & indirect immunohistochemistry

Answer 7

Direct: antibody with fluorescent tag binds to antigen (more specific)
Indirect: primary antibody binds to target antibody; secondary antibody with flourescent tag binds to primary (more sensitive)

Question 8

Explain H&E staining

Answer 8

chemical reactions between the cellular components and the dyes
blue-Hematoxylin (net positive charge) is basophilic and reacts with anionic (-) parts of cell (nuclei, heterochromatin, euchromatin, cartilage ECM)
red-Eosin (net negative charge) is acidophilic and reacts with cationic (+) parts of the cell (cytoplasm, collagen in ECM)

Question 9

Explain direct & indirect immunohistochemistry

Answer 9

Direct: antibody with fluorescent tag binds to antigen (more specific)
Indirect: primary antibody binds to target antibody; secondary antibody with flourescent tag binds to primary (more sensitive)

Question 10

Define acidophilia

Answer 10

cell that stains easily with eosin (red)

Question 11

Define basophilia

Answer 11

cell that stains easily with hematoxylin (blue)

Question 12

Epithelial tissue (structure and morphology)

Answer 12

cells are close together, rest on a basement membrane
categorized based on number of layers, shape, and special features
- simple vs stratified
- squamous, cuboidal, columnar
- cilia, microvili
functions: barrier, secretory, and absorptive

Question 13

Muscle tissue (structure and morphology)

Answer 13

large amounts of contractile products (actin, myosin)
categorized based on arrangement
     - skeletal
     - cardiac
     - smooth

Question 14

Nervous tissue (structure and morphology)

Answer 14

neurons and associated support cells

 - Schwann cells - provide myelin
 - oligodendrocytes - provide myelin
 - astrocytes - phagocytic
 - microglia - phagocytic