Connective Tissues – Supporting
Hyaline Cartilage Larynx 40X
The micrograph shows the perichondrium (arrow), which consists of a dense mass of fibroelastic connective tissue, enclosing the hyaline cartilage of the larynx. Chondroblast cells in the perichondrium secrete ground substance. When these cells become trapped in their own matrix they are called chondrocytes (Cc). Differentiation of chondroblasts and chondrocytes occurs in the subperichondrial region marked with an asterisk. Repair of damaged perichondrium involves the production of dense fibroelastic connective tissue. Damaged hyaline cartilage, because it is unable to heal, is replaced by bone.
Elastic Cartilage Epiglottis 100X
 As illustrated in the epiglottis section, elastic cartilage has a modified hyaline matrix with bunches of elastic fibers (Ef). The presence of elastic fibers in the matrix imparts strength and flexibility to the tissue. Numerous chondrocyte nuclei appear as black dots in the matrix. The perichondrium, which envelopes the cartilage, is not shown in the image.
Fibrocartilage Intervertebral Disc 400X
Fibrocartilage is a combination of dense regular connective tissue and hyaline cartilage. It is a very tough tissue containing many dense collagenous fibers (blue arrow) that alternate with rows of chondrocytes (red arrow). Within the fibrous areas, fibroblast nuclei (green arrow) are visible. Observe that the chondrocyte nuclei are larger, and they are surrounded by a small amount of amorphous ground substance. In contrast, fibroblast nuclei appear flattened or elongated, and are not surrounded by any matrix.
Compact Bone-Osteon 400X
In this section of ground bone, concentric layers of mineralized matrix called lamellae (Lm), surround the Haversian canal (Hc). Concentric arrays of almond-shaped lacunae (Lc) containing osteocytes are visible. Radiating from the Haversian canal in all directions are spaces or fine tubes called canaliculi (Cl). The anastomosing canaliculi connect lacunae to each other and to the Haversian canal. Circumferential Lamellae 100X
The circumferential lamellae (red arrows) in the light micrograph are bordered on one side by the periosteum (Pr). These lamellae extend around the entire circumference of the long bone shaft. Circumferential lamellae are located just deep to the periosteum and just superficial to the endosteum that surrounds the medullary cavity. These lamellae are formed by osteoblasts in the periosteum and endosteum regions, not by osteoblasts that create the Haversian systems. Volkmann's canal (purple arrow) can be seen communicating between the periosteum and a developing osteon, which is located in the lower left of the image. Canaliculi are barely visible at this magnification, and appear as very fine lines projecting from the lacunae (yellow arrows).
Cancellous Bone 40X
Spongy or cancellous bone is composed of anastomosing spicules or trabeculae (Tb). The medullary or marrow cavities (Mc) around the trabeculae are filled with hemopoietic tissue.
Intramembranous(IM) Ossification Mesenchyme Fetal Skull 100X
Intramembranous ossification occurs in flat bones, such as most skull bones, the mandible, and clavicles. Intramembranous osteogenesis or ossification begins when mesenchymal cells produce fibrous connective tissue membranes, which serve as a supporting framework for mineralization activities performed by osteoblasts. In the image, mesenchymal cells (Mcc) are migrating in the medullary cavity of spongy bone of the fetal skull to a region of active ossification. Mesenchymal cells give rise to bone-forming osteoblasts, which can be seen along the boundary of the matrix. Lacunae with osteocytes are present in the matrix.
IM Ossification Osteoblasts Fetal Skull 400X
At a higher magnification, a membranous trabecular surface is covered with osteoid-producing osteoblasts (Ob). Osteoblasts are eventually surrounded by their own non-calcified secretion, and become trapped in spaces in the matrix called lacunae. The osteoblasts are then known as osteocytes (arrow). Within a few days, the osteoid becomes mineralized with calcium and other mineral salts. This final ossification process creates a hardened or calcified matrix. For the most part, Haversian systems in cancellous bone are absent, except in areas where the bony matrix is very thick.
IM Ossification Howship's Lacuna Fetal Skull 400X
Bone reabsorption activity of osteoclasts (OcL) results in depressions in the bony matrix called Howship's lacunae (HL). The bone resorption process begins when osteoclasts use carbonic acid to decalcify the matrix, and release calcium ions from the mineralized bone. Osteoclasts then release hydrolytic enzymes which degrade the protein constituents, like collagen, in the matrix. After osteoclasts finish their bone remodeling activities in a particular area, they undergo apoptosis. The micrograph exhibits differentiation of osteoblasts near a blood capillary (Cp). Erythrocytes are present in the capillary.
EC Ossification Fetus 400X
Erythrocytes (arrows) and remnants of hyaline cartilage (HyC) can be identified in the primitive red marrow of a fetus femur. Endochondral ossification continues until the primary ossification center of the diaphysis fuses with the secondary ossification center of the epiphysis. Hyaline cartilage remains as the articular cartilages and the epiphyseal plates when ossification is complete. OTHER IMAGES AVAILABLE WITH THE BOOK AND CD-ROM
Hyaline Cartilage - Fetal 400X
Hyaline Cartilage - Trachea 100X
Hyaline Cartilage - Intrapulmonary Bronchus 400X
Elastic Cartilage - Epiglottis 400X
Elastic Cartilage - Ear 400X
Fibrocartilage - Symphysis Pubis 100X
Bone Compact - Osteons 100X
Bone Compact - Interstitial Lamellae 100X
Bone Compact - Osteon 400X
Bone - Haversian Canal 400X
Bone - Decalcified - Haversian Canal 400X
Bone Compact - Lacunae + Canaliculi 400X
Volkmann’s Canals 100X
Bony Matrix - Decalcified LS 40X 100X 400X
Bone - Decalcified - Volkmann’s Canal LS 400X
Bone Decalcified – Periosteum + Bony Matrix LS 100X
Bone - Periosteum 400X
Bone Marrow - Cancellous 100X
IM Ossification 100X
Osteoblast Maturation 400X
IM Ossification - Osteoblasts - Fetal Skull 100X (2 Images)
IM Ossification Osteoblasts Fetal Skull 400X
IM Ossification Osteoclasts Fetal Skull 400X (2 Images)
Endochondral(EC) Ossification Fetus 40X
EC Ossification Fetus 100X (4 Images)
EC Ossification Fetus 400X (3 Images)
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