This image shows hyaline cartilage in the wall of a bronchus. The cartilage
has anextracellular matrix composed of
fine collagen fibers and polysaccharide-rich proteoglycans. The collagen fibers
are to fine to be seen, which gives the matrix a homogeneous appearance. The
chondrocytes occupy holes in the matrix called
lacunae. Note that the chondrocytes are smaller
that the lacunae, which is an artifact of dehydration during which the cells
shrink more that the more rigid matrix. The cartilage is covered on both surfaces
by a layer of dense irregular connective tissue called the perichondrium,
containing fibroblasts and blood vessels. The cartilage matrix itself is avascular
(lacks blood vessels). The chondrocytes depend on diffusion of tissue fluid
from the blood vessels located in the perichondrium to supply them with nutrients
and remove waste products. Beneath the perichondrium is an area of cartilage
with lens-shaped (fusiform) lacunae, occupied by chondroblasts,
which are in the process of producing new cartilage matrix. Further into the
cartilage the lacunae are round and occupied by mature chondrocytes. The matrix
immediately surrounding the chondrocytes (the territorial
matrix) often stains differently from the rest of the matrix, because
it is richer in negatively charged (sulfated) carbohydrates that the rest
of the matrix (the interterritorial matrix).
