236 



ADIPOSE TISSUE. 



On the other hand, there are some parts in which fat is never found in the healthy 

 condition of the body. Thus it does not exist in the subcutaneous areolar tissue of 

 the eyelids and penis, nor in the lungs except near their roots, nor within the cavity 

 of the cranium. 



Structure. When subjected to the microscope, the adipose tissue is seen to 

 consist of small vesicles, filled with an oily matter, and for the most part lodged in 



: b 



Fig.275. A SMALL FAT-LOBULE 



FKOM THE SUBCUTANEOUS 

 TISSUE OF THE GUINEA-PIG, 

 MAGNIFIED ABOUT 20 DIA- 

 METERS. (E. A. S.) 



a, small artsry distributed 

 to the lobule ; v, small vein ; 

 the capillaries within the lo- 

 bule are not visible. 



the meshes of the areolar 

 tissue. The vesicles are 

 most commonly collected 

 into little lobular clusters 

 (fig. 275), and these again 



into the little lumps of fat which we see with the naked eye, and which in some 

 parts are aggregated into round or irregular masses of considerable magnitude. 

 Sometimes the vesicles, though grouped together, have less of a clustered arrangc- 



Fig. 276. A FEW CELLS FROM 

 THE MARGIN OF THE FAT- 

 LOBULE REPRESENTED IN 

 THE PRECEDING FIGURE : 

 HIGHLY MAGNIFIED. 



(E. A. S.) 



f-3- 



/. g, fat globule distending 

 a fat-cell ; n, nucleus ; m, 

 membranous envelope of the 

 fat-cell ; c r, bunch of crystals 

 within a fat-cell ; c, capillary 

 vessel ; v, venule ; c t, con- 

 nective tissue cell ; the fibres 

 of the connective tissue are 

 not represented. 



ment ; as when they 

 collect alongside of the 

 minute blood-vessels of 

 thin membranous parts. 

 In well - nourished 

 bodies the vesicles or 

 fat-cells are round or 



oval (fig, 276) unless where packed closely together, in which case they acquire an 

 angular figure, and bear a striking resemblance to the cells of vegetable tissues. 

 The greater number of them are from ^j^-th to ^roth of an inch in diameter, but 

 many exceed or fall short of this measurement. Each one consists of a very delicate 

 envelope (m), inclosing the oily matter, which, completely filling the envelope, 

 appears as a single drop (/. #). It often happens that a part of the fatty contents 

 .solidifies in the cell after death, forming a bunch of delicate needle-shaped crystals 

 (fig. 276, c r). 



The envelope is the remains of the original protoplasm of the cell : it is generally 

 quite transparent, and apparently homogeneous. According to some authorities it 



