AREOLAR TISSUE. 233 



or never simply spheroidal like the granular cells. Cells of the same nature but with 

 larger and more conspicuous vacuoles are met with in situations where capillary 

 blood-vessels are about to be formed (see Development of Blood-vessels). 



Cells are occasionally observed in areolar tissue in which nothing but a nucleus and a few 

 scattered granules around it are visible (fig. 262, c\ These are perhaps the remains of corpuscles 

 which are in process of disintegration, bub nothing is definitely known as to the removal and 

 regeneration of the cells of connective tissue, nor as to the genetic connection, if any, existing 

 between the several kinds of cells met with in the tissue. The three kinds of cells above 

 described all belong to the so-called " fixed cells " of the connective tissue. The " migratory 

 cells," which are occasionally seen in areolar tissue, are identical with the pale blood- or 

 lymph-corpuscles. 



In areolar tissue all the varieties of connective tissue cells above described occur. 

 They have no very definite arrangement. Both the cells and the spaces in which 

 they lie may inter-communicate by their branches, and in this way it often happens 

 where the tissue is thicker, that the system of cells and cell-processes, and of 

 corresponding canals, may effect a communication between the superficial and 

 deeper parts of the tissue. The cells of areolar tissue are also connected with the 

 flattened cells which line the smaller blood-vessels and lymphatics, and by means of 

 this connection, and the continuity of the cell-spaces of the tissue, channels are 

 provided for the flow of blood-plasma from the blood-vessels or towards the 

 lymphatics. In addition to 



this, no doubt some of the __-. r ^^^^^^_ : .- : .-.,. r ^_ i _ L _ . 



plasma or lymph may soak 



through the ground-sub- 



Btanpe, or find its way through -^oSoois^ressisfg 



^s^^rf^ , 

 the lacunar interstices (are- 



olas) of the tissue. 



In fibrous tissue (tendon 

 and ligament), the cells, which 



are Olten called ' tendon- p^ 2 7l. TENDON OP MOUSE'S TAIL, STAINED WITH LOGWOOD ; 

 cells," are all of the flattened SHOWING CHAINS OF CELLS BETWEEN THE TENDON-BUNDLES. 

 or lamellar variety. They 175 DIAMETERS. (E. A. S.) 

 follow the parallel arrange- 

 ment of the fibre-bundles, and are disposed in rows or chains (fig. 271), which 

 may be easily seen if a very fine tendon, such as those in the tail of the mouse or 

 rat, or a portion only of a larger one is examined under the microscope, and a little 

 dilute acetic acid is cautiously added. A peculiar shape is impressed upon these 

 cells by the close packing of the tendon bundles, for although they may look quad- 

 rangular or oblong when the tendon is viewed longitudinally (figs. 271, 274), yet 

 when it is cut across, they have a stellate appearance (figs. 264, 273), for like other 

 flattened connective tissue cells, they send lamellar extensions into the interstices 

 between the contiguous bundles, whilst the middle of each cell, containing the 

 nucleus, lies in the angular space between three or more bundles. When the tendon- 

 cells are viewed longitudinally, any of the lamellar extensions, which are directed 

 either towards or away from the observer, appear as lines on the surface of the cell 

 (fig. 274). The same appearance is often seen upon the flattened cells of the denser 

 forms of areolar tissue, where the cells have been squeezed in between three or more 

 bundles. 



Each tendon-cell consists of a delicate protoplasmic body, thicker at the centre 

 and thinning off in the extensions, and containing a flattened, round or oval, clear 

 nucleus, with an intranuclear network and several nucleoli. The ends of adjacent 

 cells are in close apposition, and form, as before noticed, long chains of cells in the 

 tendon, and the nucleus is generally so situated towards one end of the cell as to be 



