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Histology of muscle, cartilage and bone

By Dr. Abdul Waheed Ansari

Prof. &Chairperson Anatomy, RAKCODS. RAKMHSU.

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Learning outcomes for this labThe students are able to :• Differentiate the between the skeletal, smooth and

cardiac muscles histologically.• Classify the bone cells found in the bone tissue.• Identify the microscopic features of hyaline cartilage

and sites where they occur in the body• Compare, contrast microscopic features of elastic

cartilage and fibrocartilage. Mention the sites where they are located.

• Compare and contrast the various bone cells and their functions.

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The characteristic features of muscular tissues

• They are made up of many cells that are close together & there is little extracellular material between muscle cells.

• The muscular tissue are well vascularized.• The cells are elongated. • The cells contain myofilaments (contractile

proteins).

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Three kinds of muscle tissues

• Skeletal muscle• Cardiac muscle• Smooth muscle

• Skeletal muscle cells are very long (up to 30 cm), cylindrical, striated and multinucleated.

• The striations reflect the regular pattern of distribution of the myofilaments inside the cells.

• The nuclei are located on the periphery of the cells.

• Skeletal muscle cells are arranged in parallel, in bundles tied together by connective tissue and anchored at both ends by tendons to bones or other supporting tissues.

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Cardiac muscle cells are shorter than the skeletal muscle cells.

• Cardiac muscle cells are elongated, branched and striated.

• The striations reflect the regular pattern of distribution of the myofilaments inside the cells.

• Cardiac muscle cells have one nucleus, sometimes two at the center of the cell.

• Cardiac cells fit together tightly at dark-staining junctions called intercalated discs.

• Intercalated discs are found only in cardiac muscle tissue.

• Cardiac muscle cells are found in the heart only.

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Smooth muscle cells

• Are spindle-shaped, have one nucleus and are not striated.

• The nucleus is central in position and oval in shape.

• Smooth muscles are found in the walls of hollow organs, digestive and urinary tract organs, blood vessels, uterus.

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Hyaline cartilage• The chondrocytes lie

within chambers in the matrix called lacunae.

• The hyaline cartilage contains a gel-like amorphous matrix.

• Fine collagen fibers are present in the matrix, but they are not visible with ordinary staining technique.

• It is found at the ends of long bones .

• It supports the tip of the nose, the trachea and the bronchi.

• It forms most of the larynx and connects the ribs to the sternum.

• It is also found in epiphyseal plates of children.

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Fibrocartilage

• Fibrocartilage is quite similar to hyaline cartilage but its matrix contains many coarse collagen fibers running parallel to each other.

• It is found in pubic symphysis , intervertebral discs and the menisci of knees.

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Elastic cartilage

• Elastic cartilage is quite similar to hyaline cartilage but its matrix contains many elastic fibers.

• It is found in the epiglottis of the larynx, the external ear and the (Eustachian) auditory tubes.

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Bone histology• Bone tissue is highly vascular

where as cartilage tissue is avascular.

• An osteoblast is an immature bone cell.The osteoblast is the bone forming cell.

• A bone lining cell is a resting osteoblast.

• osteoprogenitor cells are derived from mesenchymal cells and have the ability to differentiaite into osteoblasts.

• The mature bone cell is called an osteocyte.

• An osteocyte rests in a space called a lacuna.

• An osteoclast is a multinucleated cell involved in the degradation of bone.

• It is a bone resorbing cell.• Howship's lacuna is a space

seen underneath an osteoclast.

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• A = osteoblasts,• B = osteocytes, • C = osteoid, • D = cement line • E = bone

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Histology of Compact Bone

• Compact bone is also called dense bone.

• Compact bone is composed of closely packed osteons.

• An osteon is also called a Haversian system.

• An osteon is the cylindrical structure with bone.

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Osteoclasts are the bone removing cells• They work by sealing off an

area of bone surface, when activated, they pump out hydrogen ions to produce a very acid environment, which dissolves the hydroxyapatite.

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References• http://www.zoology.ubc

.ca/~biomania/tutorial/tuthisto/smmry01.htm

• http://swc2.hccs.edu/biol/labs/ap1/tissues/elasticCart.htm

• http://www.histology-world.com/factsheets/bone1.htm

• https://casweb.ou.edu/pbell/histology/Captions/Cartilage/11.fibro.html

• http://resources.schoolscience.co.uk/mrc/osteopor/page3.html