TISSUES, ORGANS, AND SYSTEMS. 



89 



Fijr. 2 



24. Connective Tissue [fibrous and areolar tissue]. The elemen- 

 tary parts which are found in connective tissue may be divided into the 

 essential, never-failing components, and those which are met with only 

 in certain localities. To the former 

 belongs the fasciculated as well as the 

 more homogeneous connective tissue; to 

 the latter, elastic fibres in their different 

 forms and conditions of development, 

 fat cells, cartilage cells, and pigment 

 cells of different kinds. Besides these, 

 connective tissue contains also no in- 

 considerable quantity of a gelatinous 

 intermediate substance. The bundles 

 of the connective tissue are, among 

 the essential elements, those which 

 occur most frequently ; each of them 

 consists of a certain number of very 

 fine fibrils, the connective fibrils, which 

 are distinguished from their nearest 

 allies, the finest elastic fibres and mus- 

 cular fibrils, by their smaller diameter 

 (0-0003-0-0005 of a line), their pale 

 color, their homogeneous appearance, 

 and the complete absence of striation. 

 They are united by means of a small 

 quantity of a clear connecting sub- 

 stance, and thus form the bundles in 

 question, which in many respects re- 

 semble those of the transversely striated muscles, but differ from them 

 in the absence of any special investment comparable to the sarcolemma, 

 and in their smaller mean diameter (0-004-0-005 of a line.) They are 

 either long, slightly wavy cords, of uniform thickness throughout, which 

 are not directly connected together, but arranged in different ways near 

 and above one another, forming great lamellae and bundles; or they 

 coalesce like the elastic networks into meshes, and thus form what I 

 have called the reticulative connective tissue. In rare cases the bundles 

 appear not to be composed of fibrils, but are more homogeneous, as in 

 the neurilemma, where they are known as Remak's fibres. Besides this 

 form of connective tissue, there exists a second, rarer kind, in which 

 neither bundles nor fibrils can be clearly distinguished, but only a mem- 

 branous or more or less solid, finely granulated, or slightly striated, even 

 perfectly homogeneous, clear tissue ; homogeneous (or Reichert's) connec- 

 tive tissue. The other elements which occur in connective tissue pre- 



FIG. 28. Lax connective tissue with fat-cells from man; magnified 350 diam. 



