Identify the skin on the surface of the leg/thigh. The outermost layer of the skin is the epidermis; remember that feathers, like hair, are epidermal derivatives. The epidermis is a good example of stratified squamous epithelium.
Carefully skin the chicken leg. The deeper layer of the skin is the dermis, which is an excellent example of dense, irregular connective tissue. The membranous material which may cling to your hands as you work with the chicken skin is loose connective (areolar) tissue. On most chicken legs you should be able to identify another subcategory of connective tissue. Adipose tissue is found in the subcutaneous layer (also called the hypodermis) and often around the muscles.
Now examine the muscle. Note that there is a tough membrane, the deep fascia, enclosing each muscle and separating muscle groups; this is another example of dense, irregular connective tissue. Examine the muscle closely; you should be able to identify the stringy groups of muscle fibers called fascicles. Then follow a muscle to its attachment to a bone. The tendon, which attaches the muscle to the bone, is composed of dense regular connective tissue. Remember that bone is also a subcategory of connective tissue. Depending on the cut of the tissue, you may be able to identify ligaments; these connect bone to bone and are also composed of dense regular connective tissue. Also, depending on the cut, you may be able to find the menisci in the knee; these are composed of fibrocartilage, just as they are in your knees. If you have a chicken thigh, you may be able to differentiate the hamstring muscles from the anterior thigh muscle. If you have chicken leg, the gastrocnemius and soleus muscles are clearly evident as they connect to the Achilles’ tendon. Recall that cartilage is a subcategory of connective tissue; more cartilage (articular cartilage) can be identified on the chicken leg at the ends of the femur or tibia. Note the whiteness and translucent appearance of the cartilage and the menisci; this should remind you that cartilage is avascular (it lacks blood vessels).
As you try to separate the muscles, look for blood vessels and nerves. Arteries and veins are composed of epithelial lining, some connective tissue, and smooth muscle. The blood inside the vessel is also a type of connective tissue. Arteries have a much thicker smooth muscle layer and more elastic fibers than the accompanying veins. If a specimen is large enough, it is easy to feel the difference between an artery and a vein by rolling the vessel between your fingers. The artery will feel much more “springy,” while the vein will readily collapse. A nerve will appear as a whitish cord-like structure running generally parallel to the vessels. If you have a chicken thigh, you should be able to identify the sciatic nerve, the largest nerve in the body.
After removing all the tissues from the bone, wrap it in a piece of aluminum foil and weigh it. Then bake the foil-wrapped bone in a 400oF oven for at least 30 minutes. Let it cool and weigh it again. The difference is the weight of the water lost during baking. Then do the calculation: weight of water lost/weight of the fresh bone x100 = % of bone weight composed of water. If the bone is left in the oven 5-6 hours, you may have better results.
Now using the given slides identify the various tissue types of the chicken leg/thigh under the microscope.
I. Introduction of Tissues
II. Epithelial tissue
Features of epithelia
Cellularity, specialized contacts, polarity, basement
membrane, avascularity, regeneration....
Criteria-- cell shape, cellular arrangement, major classes
Simple epithelia- simple squamous, cuboidal, columnar,
Stratified epithelia- st. Squamous, cuboidal, columnar,
Glandular epithelia- endocrine, exocrine glands
III. Connective tissue
Common characteristics- common origin, degrees of vascularity, extracellular matrix
Areolar connective tissue
Fibers- collagen, elastic, and reticular
Primary blast cell types
Types of connective tissue
Embryonic- mesenchyme, mucous connective tissue
Connective tissue proper- areolar, adipose, reticular,
dense regular, dense irregular
Cartilage- hyaline, elastic, fibrocartilage
IV. Nervous tissue
Cell types- neurons, supporting cells
Types of muscle tissue- skeletal, cardiac, smooth
VI. Tissue repair
Steps of tissue repair
Regeneration and/or fibrosis
Factors affecting the repair process
THE FLUIDS OF THE BODY:
Fluid within the cells
Fluid outside of cell