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Cartilage is an avascular connective tissue specialized to provide support with some flexibility. The ground substance of cartilage is firm and compact. It consists of chondromucoprotein that stains with basic dyes. Of the three types of cartilage, hyaline cartilage is the predominant form; it occurs in more areas than either elastic cartilage or fibrocartilage.

On slide 2, Trachea (H&E), identify the hyaline cartilage which provides support for the softer tracheal tissues. The cartilage enables the trachea to maintain patency. Scan the slide with low power noting the hyaline cartilage.

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On slide 33, Lung and Bronchus (H&E), identify hyaline cartilage in the wall of the bronchus. Here there are several cartilage plates rather than one C-shaped plate.

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On slide 7, External ear (Verhoeff), identify the elastic cartilage. Verhoeff’s stain demonstrates the elastic fibers by staining them deep purple or blue-black. Note how the fibers branch, interlace and run in all directions. They diverge around the lacunae forming a network that provides the cartilage with flexibility. Although not seen in the preparation, collagenous fibers occur among the elastic fibers. The nuclei of the chondrocytes are well preserved. The cytoplasm of the cells is not stained well. Flattened lacunae occur at the periphery of the cartilage. Cell nests and isogenous groups can be identified. Observe the limits of the perichondrium.

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On slide 84, External auditory meatus (Verhoeff), identify the elastic cartilage in the wall of the external auditory tube. On this section, note that the feltwork of elastic fibers is loose and blends with the perichondrium. In this preparation, it is quite evident that the elastic fibers are more closely packed towards the center of the cartilage than at the periphery. This is a general characteristic of elastic cartilage. Note also the elastic fibers in the dense irregular connective tissue, which occupies areas between other structures.

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Identify the elastic cartilage as seen with routine H&E stain. Elastic fibers stand out clearly, densely packed in the interior of the plate, thinner and less dense at the periphery. Chondrocytes are shrunken, and many have dropped out of their lacunae.

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On slide 8, Intervertebral disc (H&E), locate the spongy bone of the vertebrae and the cartilage which unites the two bones. This cartilage consists of both the hyaline and fibrocartilage types. Fibrocartilage forms the middle portion of the disc with the articular hyaline cartilage at the periphery adjacent to the bone. The fibrocartilage stains pink in the preparation, whereas the hyaline cartilage is almost purple. Characteristic fibrocartilage is best studied at the lower border of the disc lying just outside the disc proper. The fibrocartilage in this position associates with the spinal ligaments and with tendons. Note the properties of the fibrocartilage. The chondrocytes may either lie in rows between heavy bundles of collagenous fibers or be randomly distributed. The lacunae are considerably smaller than is hyaline or elastic cartilage. Typical hyaline cartilage matrix is seen only immediately adjacent to the lacunae. It is important to remember that fibrocartilage always blends into either hyaline cartilage and/or a dense connective tissue. Also, fibrocartilage lacks a perichondrium.