The document discusses various types of connective tissues, their characteristics, and visualizations through different staining techniques. It highlights specific examples such as areolar connective tissue, adipose tissue, reticular connective tissue, and elastin fibers in the aorta, detailing their structure and function. Additionally, it covers histological methods used to observe these tissues, including H&E and Verhoeff stains.

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2. AArreeoollaarr ccoonnnneeccttiivvee ttiissssuuee
Mesentery spread – Verhoeff – 4x objective
Verhoeff’s stain is used to visualize both collagen and
elastin fibers in the same sample. Collagen fibers are
pink while elastin fibers are purple-black.
This is a loose connective tissue. See how widely spread the fibers and cells
are separated from one another.

3. AArreeoollaarr ccoonnnneeccttiivvee ttiissssuuee
Mesentery spread – Verhoeff – 10x objective
The spaces between fibers and
cells are filled with water-based
ground substance.
Elastin fiber (black arrowhead); collagen fiber (blue arrowhead); the nuclei are of
various cell types, some of which are permanent and others that wander through

4. AArreeoollaarr ccoonnnneeccttiivvee ttiissssuuee
Mesentery spread – Verhoeff – 40x objective
The loose arrangement of the
fibers gives plenty of room for
the wandering cells to pass
through the tissue.
Elastin fiber (black arrowhead); collagen fiber (blue arrowhead); the nuclei are of
various cell types, some of which are permanent and others that wander through

5. AAddiippoossee ttiissssuuee
Adipose tissue – section – H&E – 4x objective
The H-E stain requires a series of alcohol
dehydration steps. As a result, the fat droplets
within the cells are “washed out” of the sample.
You are looking at the remainder of the cell.
This honey-combed appearance is characteristic of adipose tissue.

6. AAddiippoossee ttiissssuuee
Adipose tissue – section – H&E – 10x objective
The arrowheads point out individual cells.

7. AAddiippoossee ttiissssuuee
Adipose tissue – section – H&E – 40x objective
Adipocytes are said to have a “signet ring”
appearance. Like a class ring, for example, the
stone and engraving are on one side connected
by a thin band wrapping around.
Black arrowhead – nucleus of an adipocyte; blue arrowhead – capillary within
the adipose tissue.

8. RReettiiccuullaarr ccoonnnneeccttiivvee ttiissssuuee
Spleen – section – silver – 10x objective
Reticular fibers are used to form the stroma or
framework (think infrastructure) of some
organs. For example, the spleen and lymph
nodes are made by a meshwork of reticular
fibers. Lymphocytes and macrophages then
invade the organ and take up residence in the
spaces.
Reticular tissue consists of very small collagenous fibers. They are visualized
as brownish-black fibers with the silver stain.

9. RReettiiccuullaarr ccoonnnneeccttiivvee ttiissssuuee
Spleen – section – silver – 40x objective
lymphocyte
Arrowheads point out reticular fibers. The rounded nuclei are of lymphocytes
residing in the organ.

10. RReettiiccuullaarr ccoonnnneeccttiivvee ttiissssuuee
Lymph node – section – H&E – 40x objective
Notice that with the H&E stain individual reticular fibers are difficult to visualize.
The nuclei are those of lymphocytes.

11. DDeennssee rreegguullaarr ccoonnnneeccttiivvee ttiissssuuee
Muscle-tendon intersection – section – H&E – 4x objective
muscle
dense regular
CT
The major feature you are looking for here is
the presence of pink fibers, densely packed
together, and all passing in the same plane,
parallel to one another. The nuclei of the
fibroblasts that make the fibers are fusiform in
shape, lying between the fibers.
With the H&E stain, skeletal muscle fibers ion this section are darker than the
adjacent collagen fibers.

12. DDeennssee rreegguullaarr ccoonnnneeccttiivvee ttiissssuuee
Muscle-tendon intersection – section – H&E – 10x objective
muscle
fibroblast nuclei
dense regular CT
adipose cells
Using this objective you can see that the collagen fibers are all lying in parallel
to each other, with fibroblast nuclei wedged in between the fibers.

13. DDeennssee rreegguullaarr ccoonnnneeccttiivvee ttiissssuuee
Muscle-tendon intersection – section – H&E – 20x objective
muscle
fibroblast nuclei
Using this objective you can see that the collagen fibers are all lying in parallel
to each other, with fibroblast nuclei wedged in between the fibers.

14. DDeennssee rreegguullaarr ccoonnnneeccttiivvee ttiissssuuee
Muscle-tendon intersection – section – H&E – 40x objective
muscle
fibroblast nuclei
Using this objective you can see that the collagen fibers are all lying in parallel
to each other, with fibroblast nuclei wedged in between the fibers.

15. DDeennssee rreegguullaarr ccoonnnneeccttiivvee ttiissssuuee
Muscle-tendon intersection – section – H&E – 40x objective
fibroblast nuclei
bone
collagen fibers
Another example of dense regular connective tissue. In some of the following
slides, look for it.

16. DDeennssee iirrrreegguullaarr ccoonnnneeccttiivvee ttiissssuuee
Skin – section – H&E – 4x objective
dermis
epidermis
The major feature you are looking for now is
the presence of pink fibers, less densely
packed together, and passing in multiple
directions to resist tensile forces pulling from
multiple directions.
The dermis is where we go to see the features of dense irregular connective
tissues. Look for collagen fibers passing in multiple directions.

17. DDeennssee iirrrreegguullaarr ccoonnnneeccttiivvee ttiissssuuee
Skin – section – H&E – 10x objective
epidermis
Look at all the pink-stained collagen fibers. Can you see that they are passing
in multiple directions?

18. DDeennssee iirrrreegguullaarr ccoonnnneeccttiivvee ttiissssuuee
collagen fiber passing
longitudinally
Skin – section – H&E – 40x objective
fibroblast nucleus
collagen fiber cut obliquely
collagen fiber passing out
of the screen at you
(in cross section)
In this section, you see collagen fibers passing in multiple directions. Can you
visualize how they appear in three-dimensions?

19. EEllaassttiicc ccoonnnneeccttiivvee ttiissssuuee
Aorta – section – H&E – 10x objective
The aorta is a large elastic artery. As such it has 40 – 70 layers of elastin fibers in
its wall, with some collagen fibers, and fewer smooth muscle fibers interspersed
between. All of these stain pink with H&E, so to visualize elastin fibers,
histologists use the Verhoeff stain, which preferentially stains elastin purple-black.
With the H&E stain, elastin fibers may be seen as bright pink, refractile fibers.

20. EEllaassttiicc ccoonnnneeccttiivvee ttiissssuuee
Aorta – section – Verhoeff – 10x objective
elastin fibers
In this section, you see elastin fibers, purple-black, passing circumferentially
around the aorta. See how they are coiled like a spring?

21. EEllaassttiicc ccoonnnneeccttiivvee ttiissssuuee
Aorta – section – Verhoeff – 40x objective
elastin fibers
Since this section has been counterstained with H&E, you can also see
collagen fibers and smooth muscle cells (pink), although you can’t differentiate
them.

22. HHyyaalliinnee ccaarrttiillaaggee
Trachea – cross section – H&E – 10x objective
Ciliated pseudostratified columnar epithelium
The matrix of hyaline cartilage stains a light to
dark bluish-purple with H&E. Newer matrix
(immediately adjacent to the cells) stains darker
than older matrix.
The bar with arrows indicates the thickness of the plate of hyaline cartilage
located in the wall of the trachea.

23. lumen
HHyyaalliinnee ccaarrttiillaaggee
Trachea – cross section – H&E – 40x objective
The matrix is rich in collagen (giving it a pink
color) and cartilage-specific molecules called
chondroitin sulfates (giving it a purplish color).
Arrowheads indicate chondrocytes, the cell type of cartilage. The cells sit in
spaces called lacuna and are surrounded by the matrix they have secreted.

24. EEllaassttiicc ccaarrttiillaaggee
Mouse ear – section – Verhoeff – 10x objective
Remember that the Verhoeff stain is specific of
elastin fibers, staining them purple-black.
There is a counterstain for collagen that is pink.
This is a weakly-stained specimen. In a better
preparation, the matrix would be stained
intensely purple-black.
The bar with arrows indicates the thickness of a plate of elastic cartilage
located in the ear, giving it structure and flexibiility.

25. EEllaassttiicc ccaarrttiillaaggee
Mouse ear – section – Verhoeff – 40x objective
Chondrocytes in elastic cartilage retain a fairly
high mitotic rate throughout life . As result,
there are many more cells than you would see
in hyaline cartilage.
Chondrocyte within its lacuna (arrowhead). Although a weak stain, notice all of
the dark-stained elastin fibers in the matrix.

26. FFiibbrrooccaarrttiillaaggee
Pubic symphysis –section – Mallory’s – 4x objective
All of the bluish fibers are collagen. Notice all of the rounded cells
(chondrocytes) sitting inside lacunae.

27. FFiibbrrooccaarrttiillaaggee
Pubic symphysis –section – Mallory’s – 10x objective
All of the bluish fibers are collagen. Notice all of the rounded cells
(chondrocytes) sitting inside lacunae (arrowheads).

28. FFiibbrrooccaarrttiillaaggee
Pubic symphysis –section – Mallory’s – 40x objective
lacuna
Chondrocytes (arrowhead) within its lacuna; collagen fibers (arrow)
end