VERTEBRATE SUPPORTING TISSUES 1 



1. Fibrous Connective Tissue. Examine, with the high power, a 

 prepared, transverse section of frog skin. Note that : (a) the outer portion 

 (epidermis) of the skin is made up of several layers of stratified epithelial 

 cells ; (b) the inner portion (dermis) of the skin is divided into a com- 

 paratively loose layer of connective tissue (stratum spongiosum) which 

 lies next to the epithelial cells and consists of connective tissue fibers, in 

 which are embedded numerous glands, blood vessels, and lymph spaces. 

 The remainder of the dermis consists of (c) a layer of very dense connective 

 tissue (stratum compactum) in which the bundles of wavy connective 

 tissue fibers run, in general, parallel to the surface of the skin. At intervals 

 this layer is crossed by vertical strands which extend through the stratum 

 spongiosum to the epidermis. These strands are made up of connective 

 tissue fibers and also, in some cases, of muscle fibers, nerves, and blood 

 vessels. Draw a portion of the section to show the structure as observed. 



2. Cartilage. Examine, with the high power, a prepared section of 

 hyaline cartilage. Note : (a) the transparent, homogeneous inter- 

 cellular substance (matrix) which possesses (b) numerous spaces (lacu- 

 nae). The latter contain (c) one or more nucleated cartilage cells. 

 Note also, in various regions of the preparation, that the lacunae contain- 

 ing the cartilage cells show a tendency to group together. Draw a portion 

 of the section to show the structure as observed. 



3. Bone. Examine a fresh bone, e.g., the femur of a large mammal, 

 and note its general character and the covering of cartilage at either end 

 where it forms a joint with another bone. Examine a transverse section 

 of a fresh bone and note the outer ring of bony tissue covered by the 

 delicate living periosteum and enclosing the highly vascular bone 

 marrow. 



4. Examine a permanent microscopic section of stained, decalcified 

 bone. Note (a) the intercellular matrix arranged in (6) concentric 

 layers (lamellae) and containing (c) the cell cavities (lacunae) in which 

 (d) the bone cells (osteoblasts) lie. Note further (e) the tiny branches 

 (canaliculi) of the lacunae which, in fife, contain the delicate projections 

 of the osteoblasts. (/) Haversian canals which contain blood vessels 

 may also be identified. Draw to show the structure as observed. 



1 B. pp. 172-175. 

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