36 CONNECTIVE TISSUES 



fixed or Mstogenic connective tissue cells in centra-distinction to the 

 leucocytes which wander out from the blood into the tissue spaces 

 of the connective tissues, and which are then called the wandering 

 or hematogenic connective tissue cells. These latter cells may pre- 

 sent the same varieties as the white blood cells from which they 

 are derived. 



The several varieties of connective tissue cells may be classified 



as follows : 



(a) Lamellar cells. 



I. HlSTOGENIC or FIXED. - 



(b) Spindle cells. 



(c) Plasma cells. 



(d) Granule cells. 



(e) Fat cells. 

 (/) Pigment cells. 

 . (g) Embryonic stellate cells. 



II. HEMATOGENIC or wAN-( /7X T 



\ (Ji) Leucocytes. 

 DEEING. ( v ' 



Types of Connective Tissue. The proportions and character of 

 the cells and fibres present in any given connective tissue, to a 

 certain extent, determine its character. If the white fibres of con- 

 nective tissue are closely packed in dense parallel bundles, the 

 elastic fibres being comparatively insignificant in number, the 

 type of connective tissue may then be said to be dense fibrous or 

 white fibrous tissue. 



In elastic tissue, on the other hand, the yellow elastic fibres are 

 highly developed, the white fibres forming only insignificant and 

 very delicate sheaths, which inclose the coarser elastic fibres. 



Again, it is the variety of delicate connective tissue fibre known 

 as reticulum which preponderates in reticular tissue, and if the 

 meshes of this reticular network become infiltrated by leucocytes, 

 which then multiply by division until they exceed the other tissue 

 elements, the connective tissue is then said to be of the lymphoid 

 or adenoid variety. In all we distinguish the following varieties of 

 connective tissue : 1, embryonic; 2, gelatinous ; 3, areolar ; 4, dense 

 white fibrous ; 5, elastic ; 6, adipose ; 7, reticular ; 8, lymphoid. 



Embryonic connective tissue (Figs. 32 and 33) occurs not only 

 in fetal and infantile life, but also during the regeneration of de- 

 stroyed connective tissue areas and in pathological neoplasms. It 

 is distinctly cellular in character. Its cells are spindle-shaped and 

 stellate, are much branched, and, through their larger processes, 

 they frequently anastomose. 



