HISTOLOGY REVIEWHISTOLOGY REVIEWConnective TissuesConnective Tissues
Dr. Tim BallardDr. Tim Ballard
Department of Biology and Marine BiologyDepartment of Biology and Marine Biology
Mesentery spread – Verhoeff – 4x objective
This is a loose connective tissue. See how widely spread the fibers and cells are separated from one another.
Areolar connective tissueAreolar connective tissue
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.
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
Mesentery spread – Verhoeff – 10x objective
Areolar connective tissueAreolar connective tissue
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
Mesentery spread – Verhoeff – 40x objective
Areolar connective tissueAreolar connective tissue
The loose arrangement of the fibers gives plenty of room for the wandering cells to pass through the tissue.
Adipose tissue – section – H&E – 4x objective
This honey-combed appearance is characteristic of adipose tissue.
Adipose tissueAdipose tissue
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.
Adipose tissue – section – H&E – 10x objective
The arrowheads point out individual cells.
Adipose tissueAdipose tissue
Adipose tissue – section – H&E – 40x objective
Black arrowhead – nucleus of an adipocyte; blue arrowhead – capillary within the adipose tissue.
Adipose tissueAdipose tissue
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.
Spleen – section – silver – 10x objective
Reticular tissue consists of very small collagenous fibers. They are visualized as brownish-black fibers with the silver stain.
Reticular connective tissueReticular connective tissue
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.
Arrowheads point out reticular fibers. The rounded nuclei are of lymphocytes residing in the organ.
lymphocyte
Spleen – section – silver – 40x objective
Reticular connective tissueReticular connective tissue
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.
Reticular connective tissueReticular connective tissue
Muscle-tendon intersection – section – H&E – 4x objective
With the H&E stain, skeletal muscle fibers ion this section are darker than the adjacent collagen fibers.
Dense regular connective tissueDense regular connective tissue
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.
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.
Dense regular connective tissueDense regular connective tissue
Muscle-tendon intersection – section – H&E – 10x objective
muscle
dense regular CT
adipose cells
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.
Dense regular connective tissueDense regular connective tissue
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.
Dense regular connective tissueDense regular connective tissue
Muscle-tendon intersection – section – H&E – 40x objective
muscle
fibroblast nuclei
Dense regular connective tissueDense regular connective tissue
Muscle-tendon intersection – section – H&E – 40x objective
fibroblast nuclei
collagen fibers
bone
Another example of dense regular connective tissue. In some of the following slides, look for it.
Dense irregular connective tissueDense irregular connective tissue
The dermis is where we go to see the features of dense irregular connective tissues. Look for collagen fibers passing in multiple directions.
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.
Dense irregular connective tissueDense irregular connective tissue
Look at all the pink-stained collagen fibers. Can you see that they are passing in multiple directions?
Skin – section – H&E – 10x objectiveepidermis
Dense irregular connective tissueDense irregular connective tissue
In this section, you see collagen fibers passing in multiple directions. Can you visualize how they appear in three-dimensions?
collagen fiber passing
longitudinally
collagen fiber passing out of the screen at you
(in cross section)
collagen fiber cut obliquely
fibroblast nucleus
Skin – section – H&E – 40x objective
Elastic connective tissueElastic connective tissue
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.
Elastic connective tissueElastic connective tissue
In this section, you see elastin fibers, purple-black, passing circumferentially around the aorta. See how they are coiled like a spring?
elastin fibers
Aorta – section – Verhoeff – 10x objective
Elastic connective tissueElastic connective tissue
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.
elastin fibers
Aorta – section – Verhoeff – 40x objective
Trachea – cross section – H&E – 10x objective
The bar with arrows indicates the thickness of the plate of hyaline cartilage located in the wall of the trachea.
Hyaline cartilageHyaline cartilage
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.
Arrowheads indicate chondrocytes, the cell type of cartilage. The cells sit in spaces called lacuna and are surrounded by the matrix they have secreted.
lumen
Trachea – cross section – H&E – 40x objective
Hyaline cartilageHyaline cartilage
The matrix is rich in collagen (giving it a pink color) and cartilage-specific molecules called chondroitin sulfates (giving it a purplish color).
Mouse ear – section – Verhoeff – 10x objective
Elastic cartilageElastic cartilage
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.
Mouse ear – section – Verhoeff – 40x objective
Elastic cartilageElastic cartilage
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.
Pubic symphysis –section – Mallory’s – 4x objective
All of the bluish fibers are collagen. Notice all of the rounded cells (chondrocytes) sitting inside lacunae.
FibrocartilageFibrocartilage
Pubic symphysis –section – Mallory’s – 10x objective
FibrocartilageFibrocartilage
All of the bluish fibers are collagen. Notice all of the rounded cells (chondrocytes) sitting inside lacunae (arrowheads).
lacuna
Pubic symphysis –section – Mallory’s – 40x objective
FibrocartilageFibrocartilage
Chondrocytes (arrowhead) within its lacuna; collagen fibers (arrow)end
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