50 THE ESSENTIALS OF HISTOLOGY. 



LESSON XL 



THE CONNECTIVE TISSUES (continued). 



ARTICULAR CARTILAGE. 



1. COT two or three very thin tangential slices of the fresh cartilage of a joint, 

 mount them in saline solution or serum, and examine with a high power. 

 Observe carefully the form and grouping of the cells. Look at the thin edge 

 of the section for spaces from which the cells have dropped out. Measure 

 two or three cells and their nuclei, and sketch one or two groups. Now 

 replace the saline solution by water and set the preparation aside for a little 

 while. On again examining it, many of the cartilage-cells will be found to 

 have shrunk away from their containing capsules. . 



2. Make other sections of the cartilage (1) from near the middle, (2) from 

 near the edge. Place the sections for two or three minutes in acetic acid 

 (1 per cent.), wash them with water, and stain with dilute haematoxylin 

 solution. When stained mount in dilute glycerine and cement the cover- 

 glass. In (2) look for branched cartilage-cells. Draw one or two. 



3. Make vertical sections of articular cartilage from a bone which has 

 been for several days in per cent, chromic acid solution, and mount the 

 sections in glycerine and water, or, after staining, in Canada balsam. 1 

 Sketch the arrangement of the cells in the different layers. 



4. Wash a fresh joint with distilled water ; drop 1 per cent, nitrate of silver 

 solution over it ; after five to ten minutes wash away the nitrate of silver 

 and expose in water to direct sunlight. When browned, place in spirit for 

 half an hour or more, and then with a razor wetted with spirit cut thin 

 sections from the surface and mount in Canada balsam after passing through 

 clove-oil. The cells and cell-spaces show white in the brown ground- 

 substance. Draw. 



Cartilage or gristle is a translucent bluish-white tissue, firm, and at 

 the same time elastic, and for the most part found in connection with 

 bones of the skeleton, most of which are in the embryo at first repre- 

 sented entirely by cartilage. Two chief varieties of cartilage are 

 distinguished. In the one, which is termed hyaline, the matrix or 

 ground-substance is clear, and free from obvious fibres ; in the other, 

 which is termed fbro-carlilage, the matrix is everywhere pervaded by 

 connective-tissue fibres. When these are of the white variety, the 

 tissue is white fibro-cartilage ; when they are elastic fibres, it is yellow or 

 elastic jibro-cartilage. 



1 See Appendix. 



