Histology Pictures Flashcards
Areolar
Collagen Fibers
(thick wavy bundles, blue)
Elastic fibers
Sheets of elastic fibers, called elastic lamellae, are common in the aorta, shown here. These lamellae give a distinctive refractive appearance when you focus through them.
Reticular fibers
are composed of type III collagen, and appear black with a silver stain. In many organs and basement membranes, they provide a supportive framework.
Loose Connective Tissue
The loose CT in the duodenum (see the Brunner’s glands?) is a “space filler” that provides the flexibility the GI tract needs. Many of the nuclei present are probably fibroblasts, but other cell types common in loose CT include plasma cells, mast cells, and lymphocytes.
Loose Connective Tissue
Loose CT is also found in the mesentary (surrounding the blood vessels and Pacinian corpuscle), and in addition to the cell types mentioned previously, loose CT may include adiopocytes.
Bar = 250 Microns
Dense Irregular CT
Compare this with the previous two slides if you have any questions about the definitions of “loose” or “dense.”
Bar = 250 Microns
Tendon
In cross section, collagen fibers make up the pale pink background. The fine lines separate fiber bundles; numerous fibroblast nuclei can be seen.
Bar = 50 Microns
Tendon
Longitudinally, wavy fibroblasts run along the tendon. Recall that the collagen and elastic fibers of the tendon are extracellular.
Bar = 100 Microns
Tendon
Here the tendon has far fewer fibroblasts. Notice presence of skeletal muscle marks the point of insertion.
Bar = 100 Microns
Tendon
Typically the tendon is characterized by fibroblasts in regular, parallel arrangements, as shown here. These are often described as “boxcars” in a line (at least by railroad aficionados). Look Alikes: Smooth Muscle, Skeletal Muscle, Nerve.
Bar = 100 Microns
Umbilical Cord
The two arteries and one vein (upper left) of the umbilical cord are surrounded by a large amount of connective tissue. The proportion of “ground substance” is higher in this tissue, and it is sometimes called “Wharton’s jelly”.
Umbilical Cord
A closer look shows the preponderance of ground substance (largely glycoproteins and proteoglycans) and relatively few cells.
Bar = 100 Microns
Hyaline
Hyaline cartilage is distinguished by its homogenous matrix surrounding the small nests of chrondrocytes. Notice the perichondrium which surrounds hyaline cartilage.
Bar = 250 Microns
Hyaline
Chondrocytes develop in the perichondrium (to the left). As they mature, they are moved deeper into the cartilage. There they actually secrete the matrix that traps them. Isogenous groups (small nests of chrondrocytes) result from repeated cell division.
Bar = 250 Microns
Hyaline
Again, note the homogeneity of the matrix and identify the isogenous groups (red arrows).
Bar = 100 Microns
Elastic
This pink strip of tissue is cartilage containing numerous elastic fibers. These fibers possess a refractile appearance when focusing through them on the microscope.
Bar = 250 Microns
Elastic Cartilage
A closer look shows the heterogeneity of the matrix. Again confirm elastic fibers by focusing through them on the actual microscope.
Bar = 50 Microns
Elastic
The elastic fibers are more difficult to see here on a static digital image. Let this serve as a reminder to get in the habit of focusing through all tissues on the microscope.
Bar = 100 Microns
Elastic Cartilage
Here the elastic fibers are a little easier to distinguish.
Bar = 100 Microns
Fibrocartilage
Fibrocartilage ideally assumes a herring bone pattern. It has a linear orientation related to it’s function. Always look for the isolated chondrocytes in their lacunae.
Bar = 250 Microns
Fibrocartilage
A closer look better reveals the herring bone pattern. Notice also that fibrocartilage has no perichondrium.
Bar = 100 Microns
Fibrocartilage
Fewer and smaller chondrocytes than elastic or hyaline cartilage. Note there are no isogenous groups.
Bar = 250 Microns
Developing Skull
In intramembranous ossification, bone forms without a cartilage intermediate (i.e. directly from mesenchyme). In this slide, bone spicules are observed with osteoblasts (blue arrows) along their surfaces and osteocytes (green arrows) trapped within the calcified matrix. Marrow cells are identified with the red arrow.
Bar = 100 Microns
Epiphysial Growth Plate
The epiphysial growth plate, where cartilage is removed and bone is formed, is marked by four stages (left to right): resting zone, proliferative zone, hypertrophy zone, ossification zone.
Bar = 250 Microns
Developing Long Bone
In this trichrome stained section, calcified cartilage forms the cores of spicules with bone deposited on the outside. This slide is taken from the ossification zone of a developing long bone.
Bar = 250 Microns
Haversian Canals
This dry ground section shows the Haversian canal system. Notice the osteocytes trapped in each concentric layer which has been laid in successive waves. In this preparation the calcium salts have not been removed.
Bar = 250 Microns
Haversian Canal
A higher magnification view of slide 4 clearly shows the concentric circles. After osteoclasts remove old bone, osteoblasts deposit bone in this circular arrangement beginning with the outer ring and working inward. As the osteoblasts become trapped in their own calcified deposits, they are known as osteocytes.
Bar = 100 Microns
