CONNECTIVE TISSUES. 23 
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poe ear and bundles, and gives support to all the organs of the 
ody. 
How is it made up microscopically . 
Of a homogeneous ground substance in which white and yellow elastic 
fibres cross and interlace in every direction. The density and strength 
of a particular piece of the tissue depends upon the number of these 
fibres and the closeness of their arrangement. Between the fibres in 
the ground substance we find cells of different shapes and sizes, the 
connective tissue cells proper. 
What is the ground substance of connective tissue ? 
The ground substance or intercellular substance is composed of a 
soft, homogeneous material occurring between the cells and in which 
the fibres lie. It serves as a cement substance to hold the cells and 
fibres together. When the fibrous elements are very abundant the 
ground substance is obscured. 
Name the varieties of cells in connective tissue ? 
Flattened or lamellar, granular, and vacuolated or plasma cells, 
Describe the flattened or lamellar cells ? 
Some are flat and are applied to the surfaces of bundles of white 
fibres, others are between these bundles and have peculiar wing-like 
processes thrust out between bundles of fibres. 
Describe granular cells ? 
They are corpuscles containing granules in the cell-body and are 
found especially abundant near bloodvessels. 
Describe the vacuolated or plasma cells? 
They contain numerous vacuoles or small holes in the cell-proto- 
plasm, thus differing from the two preceding types. These vacuoles 
are filled with a fluid resembling lymph, or blood plasma. 
What is the structure of embryonal connective tissue ? 
It is composed of small round cells, having no definite arrangement, 
and lying in a homogeneous intercellular substance. In this inter- 
cellular substance are numerous fine fibres or fibrillee. 
How is this tissue formed ? 
The mesoblastic cells, which are to form connective tissue, are 
loosely packed together with an albuminous fluid between them ; later 
this fluid becomes more consistent, and little fibrils are formed in it. 
