Bio 207 Histology Workshop
Goals: --To familiarize you with some of the tissues most susceptible to cancer.
--To contrast normal and cancer tissues.
--To demonstrate different levels of structure and function in the human body.
Background:
Histology is the study of tissues. Histology is the area of biology that falls
between anatomy (the study of organs and organ systems) and cell biology (the study of
the cells that make up tissues). The major tissue types are the epithelia--tissues that form
the linings and coverings of the body, connective tissues--those that underlie the epithelia
and form much of the “substance” of body structures, muscle tissues--those involved in
movement or stretching and nervous tissues--those involved in signaling in the nervous
system.
Where do histological slides come from? Start with a particular organ--for
example, the lung. To prepare a section of lung for histology, lung tissue was preserved in
some way and embedded in paraffin or a plastic medium. Then the tissue was cut into
very thin sections using a sharp blade (called a microtome). Finally the embedding
medium is cleared away and the section is stained, most commonly with hematoxylin and
eosin stains. These give a pink color to the cells and stain the nuclei darker than the rest
of the cell (often blue or purple).
One of the most difficult aspects of histology is figuring out what you are looking
at. What do you see when you look at a section of lung tissue under the microscope?
First we need to recall what the lung does and what its role is in the respiratory system.
The respiratory system provides oxygen to the body. It does so by conducting oxygen
through a series of tubes (from the mouth and nose to the pharynx, trachea and bronchi).
The last of these tubes, the bronchi, branch into smaller ducts in the lungs (the
bronchioles) ultimately ending in air sacs called alveoli. Thus in a section of lung tissue
you will see mostly cells of the alveoli and bronchioles, along with blood vessels (in order
for oxygen to go from the lungs to the heart and out to the various parts of the body, the
blood vessels must come in close proximity to the lungs).
What does histology have to do with cancer? In cancer cells are growing out of
control. They begin to look and act differently from the cells around them. With current
technologies, it is not possible to detect cancer cells at the very earliest stages--these cells
look the same as normal cells! Removing tissue samples from a patient, preparing
histological sections and observing abnormal cells is how most cancers are currently
diagnosed. Most cancers affect epithelial tissues and are often designated as carcinomas.
Cancers of the connective tissues and muscle are more rare and are usually referred to as
sarcomas. Although blood is considered to be a type of connective tissue, since it must
be constantly replenished, it contains many rapidly dividing cells that can become
cancerous. Cancers of the circulating blood cells are called leukemias, while solid tumors
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of blood cells lodged in particular organs are called lymphomas. You will see today to
how some of these different cancers affect the structure and appearance of tissues.
Workshop procedure:
Part 1 Lung Cancer: An example to contrast normal vs. cancer tissue
1. We will first briefly run through how to use the microscope, focusing on a slide of
human lung.
2. Look at the lung tissue in the slide and compare to the picture of lung cancer on the
demonstration slide. What are the differences?
Part 2 Histology of epithelial tissues
Once you are familiar with the microscopes, use them to identify the major types of
epithelia. Epithelia are among the tissues most prone to cancer and are also the most
easily identified of the different tissue types. Cancers of the epithelia are called
carcinomas. Identify the major types of epithelia, esp. simple squamous, simple cuboidal
and simple columnar, on the various slides using the following handout as a guide.
Glandular tissue is also an epithelium and can be found in the breast, prostate, and other
organs; cancers of glands are often called adenocarcinomas.
Slides to look at
Epithelial type
1.
lung (alveolar cells and
endothelial cells of a capillary)
simple squamous
2.
kidney (ductal cells)
simple cuboidal
3.
intestine (cells of intestinal
lining)
simple columnar
Part 3 Compare normal and cancer tissues
1. Each pair of students will be given two slides, one of a normal tissue section
(LABELED #A) and one of the corresponding tissue affected by cancer (LABELED #B).
Try to get your slide in focus, look at it briefly, then look at that of your partner. You
may want to stay with lower power objectives at first to try to scan around and figure out
what you’re looking at. If you are assigned a slide of a leukemia or lymphoma, first get
your slide in focus under the 40x objective (400x magnification) and then ask the
instructor to help you add immersion oil and switch to the oil immersion lens (100x
objective) for optimal viewing.
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2. Begin to figure out what you are looking at by comparing the normal slide to pictures
in histology or anatomy texts, available at the lab tables.
3. Start to note some of the differences between the normal tissue slide and the cancer
tissue slide. Your notes and drawings can be used in answering the questions in the
assignment.
4. Time permitting, you may want to move around the lab to see some of the slides
representing other cancers and to talk with other students to see how they are approaching
the assignment. You may want to view images of many of the slides available online in
the cancer histology database at http://aristotle.oneonta.edu/coppermine/index.php
The slides available include:
Slide label
(1A) human lung
(1B) human bronchogenic carcinoma
(2A) skin cornified
(2B) human basal cell carcinoma
(3A) human lung
(3B) human adenocarcinoma of the lung
(4A) stomach fundus human
(4A) stomach and duodenum
(4B) human carcinoma of stomach
(5A) ileum human
(5B) human carcinoma of colon
[(6A) skin human pigmented and non-pigmented]
[(6B) human malignant melanoma of skin]
[Slide not available]
(7A) peripheral blood smear
(7B) human acute monocytic leukemia
(8A) ovary human
(8B) human adenocarcinoma of ovary
(9A) mammary gland active
(9B) human fibroadenoma of the breast
(10A) uterus human progravid phase
(10B) human adenocarcinoma of endometrium
(11A) bladder human
(11B) transitional cell carcinoma bladder
(12A) prostate young human
(12B) human carcinoma of prostate
(13A) peripheral blood smear
(13B) lymphatic leukemia acute blood smear
(14A) peripheral blood smear
(14B) human chronic lymphocytic leukemia smear
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In lay terms
lung cancer
common skin cancer
lung cancer
stomach cancer
colon cancer
melanoma (lethal skin
cancer)
leukemia (cancer of blood)
ovarian cancer
breast cancer
endometrial cancer
bladder cancer
prostate cancer
leukemia
leukemia
(15A) lung human
(15B) human alveolar cell carcinoma
(16A) uterus human follicular phase
(16B) human sarcoma of uterus
(17A) peripheral blood smear
(17B) Hairy Cell leukemia
(18A) mammary gland active
(18B) human adenocarcinoma of breast
(19A) peripheral blood smear
(19B) myeloblastic leukemia acute blood smear
(20A) mammary gland human
(20B) human adenocarcinoma of the breast
(21A) trachea and esophagus
(21B) human carcinoma of esophagus
(22A) larynx
(22B) human carcinoma of larynx
(23A) peripheral blood smear
(23B) lymphoma smear
(24A) kidney
(24B) kidney carcinoma
lung cancer
uterine cancer
leukemia
breast cancer
leukemia
breast cancer
esophageal cancer
cancer of the larynx
lymphoma
kidney cancer
If you would like additional time to view the slides, or additional help in identifying the
cancers in the slides, please arrange to meet the instructor during office hours or by
appointment. I will try to schedule these for the microscope imaging station so we can
capture what we see under the microscope.
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Bio 207 HistologyWorkshop
Questions (20 points)
After completing the workshop, research your answers to the following questions,
then briefly print or type your answers on separate pages. Be sure to cite any references
you consulted (by author, year, title, volume, pages for journal or book or by URL address
for web sources). You may download images from the Coppermine Cancer Histology
Image Database (http://aristotle.oneonta.edu/coppermine/index.php)
or from other internet sites to illustrate your answers. Due in class by Monday Sept. 14,
2009
1. Most types of cancers affect epithelial tissues. Why are epithelia most often affected?
2. Describe the major types of epithelial tissues. You may use your own illustrations, if
you wish.
The following questions are based on the cancer and normal tissue slides you were
assigned during the workshop.
3. For the normal tissue slide you were assigned, determine where in the body (what
organ or organ system and the location) it would be found. Describe, draw, or illustrate
with images the relationship between the organ and the section you are looking at.
4. Identify the major cell types in the tissue, their organization (if any) and their
functions? Which cells in the tissue might be rapidly dividing and thus more likely to
become cancerous?
5. Compare your assigned cancer tissue slide to the normal tissue slide. What is the
difference? Document in words, illustrations, and/or images the differences you see
between the two..
6. How far has the cancer progressed? Do you have any evidence from your slide that
the cancer has become metastatic? Include cancer slide images or drawings to illustrate
your answer. What are some of the limitations of using tissue biopsy and observation of
histological slides as a means of detecting and diagnosing cancers?
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