26 CLASSIFICATION OF TISSUES. 
What is the structure of hyaline cartilage ? 
The bulk of it is made up of a homogeneous material or matrix, 
which is perfectly structureless. In this are rounded or oval cell- 
bodies scattered irregularly. These cells have a round nucleus and 
may have more than one. ; 
The cells are contained in cavities in the matrix, which cavities 
they cntirely fill in the fresh state. 
What are common modifications of the structure of hyaline 
cartilages ? 
In the costal and articular cartilages the cells are arranged in groups 
and the matrix sometimes appears granular. Near the margin of 
attachment between articular cartilage and connective tissue, the car- 
tilage cells are sometimes branched. 
Where is yellow elastic cartilage found in the human body ? 
In the epiglottis, the cartilages of the ear, and Eustachian tube, and 
in the cornicula of the larynx. 
What is its microscopical structure ? 
It differs from hyaline cartilage in that the matrix is everywhere 
traversed by fibres of yellow elastic tissue. Intermixed with these are 
small plates of hyaline material, each containing a single cartilage cell. 
Where is white fibrocartilage usually found ? 
In the marginal cartilages by which the shoulder and hip joints are 
deepened. In the inter-articular cartilages of the spinal column, knee 
joint, and joint of lower jaw. 
What is the structure of this form of cartilage ? 
It is made up of white fibrous tissue just as tendonis. Between the 
fibres are cartilage cells singly or in groups, each embedded in a small 
plate of hyaline material. 
Are there any vessels or nerves in cartilage ? 
There are no nerves, and in articular cartilages there are no blood- 
vessels, In large masses of cartilage are canals here and there in 
which bloodvessels run. These canals are very few in number. 
What are the principal parts of bone? 
Tts covering or periosteum. 
The hard or earthy part, and the marrow. 
Name the two general varieties of the hard part of bone. 
Compact bone and cancellous or spongy bone, 
