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KMID : 0376219840210030513
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Chonnam Medical Journal
1984 Volume.21 No. 3 p.513 ~ p.537
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The Fine Structure of the Meniscus of the Rat
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Abstract
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The structural differences between the meniscal body and horns of the growing rat were studied by electron microscopy. Anterior and posterior horns were constituted of parallel collagen fibers with interspersed fibroblasts. The fibroblasts possessed rough endoplasmic reticulum, a moderate number of mitochondria, free ribosomes, and a prominent Golgi apparatus.
The center of meniscal body grew from undifferentiated mescenchyme to cartilage, calcified cartilage, and bone by a process of endochondral ossification. The inner two thirds of the meniscal body were filled with circumferentially oriented fibers of collagen and flattened chondrocytes.
In fibrocartilage region between horn and body, fibrocartilage cells gradually changed into chondrocytes. The shape is changed from flat to oval and most cells arranged themselves in pairs or rows.
In contrast to hyaline cartilage, fibrocartilage zone contained more densely packed collagen fibers which branched wavy and abundant ground substances. The fibrocartilage cells contained rough endoplasmic reticulum, the Golgi apparatus, and secretory granules. At the site of initial calcification, a large number of matrix vesicles occurred among the collagen fibrils. The first identifiable needles of apatite crystals were deposited in and close to the matrix vesicles.
Where calcification was more extensive, the crystals radiating from each calcification center formed a calcified spherule. Chondrocytes in mineralized fibrocartilage remained active despite partial enclosure by mineralized matrix.
The outer side of the meniscus was constituted of cross bundles of collagen fibers and fibrocytes. The scanning electron microscopy showed that the ridges and furrows were more marked at the horns and outer side of the meniscus.
The neurovascular supply was absent in the body, but abundant in the horns and outer side of the meniscus.
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