CONNECTIVE TISSUE. 69 



(1) HYALINE CARTILAGE. 



THis is characterized by a bluish- white, semi-transparent matrix, 

 free from fibres It occurs in costal cartilages, the articular ends of 

 bone, the trachea, bronchi, larynx, the auditory meatus, and in the 

 early cartilage of the foetus. 



Laboratory exercise No. 19. Hyaline cartilage. Harden pieces of 

 costal cartilage, or of the sternum of a newt, in picric acid; embed in 

 celloidin; stain with hsematoxylin, method No. 5, or carmine, method 

 No. 2. Examine with L. P. and note the following- structures: (1) The 

 perichondrium with its fibrous and chondrogenetic layers; (2) the 

 matrix, free from fibres, in which are embedded the cells; (3) the cells, 

 lying in their lacunaB with inclosing capsule, and arranged in groups 

 of two or more. Compare the form, size, and disposition of the more 

 centrally located cells with those toward the surface. Do you observe 

 nucleoli? Drawings. 



(2) ELASTIC CARTILAGE. 



This form is characterized by the presence of yellow elastic fibres 

 in the matrix, They first appear as minute granules, which arrange 

 themselves in linear rows and, coalescing, form the fibres. The 

 color of the matrix is yellowish. Elastic cartilage occurs-:- in the 

 epiglottis, the external ear, the Eustachian tube, etc. 



Laboratory exercise No. 20. Elastic cartilage. Harden portions of 

 the ear of a pig in picric acid, embed in celloidin, and stain with hsema- 

 toxylin, method No. 5. Observe, as in the preceding preparation, the 

 perichondrium, matrix, and cells. Note also the yellow, interlacing 

 fibres, which extend from the matrix into the perichondrium. Minute 

 granules of elastin will also be seen with the high power. Make out 

 the capsule, lacuna, and cell structure. Prepare drawings to illustrate 

 all of these structures. 



(3) FIBRO-CARTILAGE. 



Here we have the same structures as exhibited in hyaline carti- 

 lage, but the matrix is provided with many bundles of white fibres, 

 running in different directions and interlacing. It occurs In the 

 intervertebral disks, sesamoid bones, etc. 



Laboratory exercise No. 21. Fil)ro-cartilage. Decalcify and harden 

 with picric acid pieces of the vertebral column of a cat so as to include 

 the intervertebral disk, or use the intervertebral disk of an ox. Freeze 

 or embed in celloidin. Stain with lithium carmine, method No. 2. 

 Examine and note the numerous bundles of wavy fibres, between which 



