(C22, 23) Slide 98: Meniscus of the knee H&E

This slide and the next are examples of fibrocartilage, which resembles dense connective tissue. The best way to distinguish fibrocartilage from dense CT is to look for the lacunae and isogenous groups. Cartilage has cells in lacunae and dense CT does not. The cells of dense connective tissue are never clumped together like they are in cartilage. When compared with dense regular connective tissue like that of a tendon, chondrocytes are more numerous.

Fibrocartilage comes in three flavors (i.e. It takes on three different morphological appearances). One will be seen on this slide (a woven arrangement) and two will be on the next slide (one with a "herringbone" arrangement and the other with parallel, aligned bundles). The cells in each of these arrangements will present groups of chondrocytes in a linear row. To distinguish fibrocartilage from hyaline and elastic cartilage, it is best to look at the big bundles of type I collagen. Remember that hyaline and elastic cartilage are composed of type II collagen, which does not form fibers and fibrocartilage contains fiber forming, type I collagen.

Now look at the glass slide. Initially, use a medium magnification of 10 or 20x to get a good feel for the woven arrangement of the collagen bundles (C22). You should find isogenous groups here as well. The woven arrangement of the collagen bundles serves to reinforce the cartilage and allows it to withstand the compressive, pounding pressures generated at the knee. Some run parallel to the plane of section, while others are oblique (no pun intended- run at the knee for the slower group). Typically you can only see a few of these linearly arranged chondrocytes between the dense type I collagen bundles before they leave the plane of section (C23).