Tissue Processing (Junqueira)

Question 1

Tissues have two interacting components:

Answer 1

cells
extracellular matrix (ECM).

Question 2

consists of many kinds of macromolecules, most of which form complex structures, such as collagen fibrils.

Answer 2

Extracellular Matrix - ECM

Question 3

supports the cells and contains the fluid transporting nutrients to the cells, and carrying away their wastes and secretory products.

Answer 3

Extracellular Matrix - ECM

Question 4

Small pieces of tissue are placed in solutions of chemicals that cross-link proteins and inactivate degradative enzymes, which preserve cell and tissue structure.

Answer 4

Fixation:l

Question 5

The tissue is transferred through a series of increasingly concentrated alcohol solutions, ending in 100%, which removes all water.

Answer 5

Dehydration

Question 6

Alcohol is removed in organic solvents in which both alcohol and paraffin are miscible.

Answer 6

Clearing

Question 7

The tissue is then placed in melted paraffin until it becomes completely infiltrated with this substance.

Answer 7

Infiltration

Question 8

The paraffin-infiltrated tissue is placed in a small mold with melted paraffin and allowed to harden.

Answer 8

Embedding

Question 9

The resulting paraffin block is trimmed to expose the tissue for sectioning (slicing) on a microtome

Answer 9

Trimming

Question 10

is used for sectioning paraffin-embedded tissues for light microscopy

Answer 10

microtome

Question 11

The trimmed tissue specimen is mounted in the paraffin block holder, and each turn of the drive wheel by the histologist advances the holder a controlled distance, generally from

Answer 11

1 to 10 μm

Question 12

For TEM, sections less than 1 μm thick are prepared from resin-embedded cells using an _______ with a glass or diamond knife.

Answer 12

ultramicrotome

Question 13

Before infiltration with such media, the fixed tissue must undergo dehydration by having its water extracted gradually by transfers through a series of increasing ethanol solutions, ending in

Answer 13

100% ethanol

Question 14

The ethanol is then replaced by an organic solvent miscible with both alcohol and the embedding medium, a step referred to as______ because infiltration with the reagents used here gives the tissue a translucent appearance.

Answer 14

clearing

Question 15

The fully cleared tissue is then placed in_______ in an oven at______, which evaporates the clearing solvent and promotes infiltration of the tissue with paraffin

Answer 15

melted paraffin

52°-60°C

Question 16

Embedding materials include paraffin, used routinely for_____

Answer 16

light microscopy

Question 17

plastic resins, are adapted for both
___\ and _____ microscopy

Answer 17

light and electron microscopy

Question 18

Embedding is allowing it to harden in a small container of paraffin at

Answer 18

room temperature

Question 19

Tissues to be embedded with plastic resin are also dehydrated in ethanol and then infiltrated with plastic solvents that harden when cross-linking_______ are added.

Answer 19

polymerizers

Question 20

avoids the higher temperatures needed with paraffin, which helps avoid tissue distortion.

Answer 20

Plastic embedding

Question 21

Paraffin sections are typically cut at_____ thickness for light microscopy

Answer 21

3-10 μm

Question 22

electron microscopy requires sections less than _____ thick.

Answer 22

1 μm

Question 23

The sections are placed on glass slides and stained for light microscopy or on metal grids for electron-microscopic staining and examination

Answer 23

Mounting