74 



HISTOLOGY 



rounded form as shown in Fig. 60; often, however, their thin walls are 

 bent or collapsed. If the sections are thick, a network of a different 

 pattern, representing another layer of cells, will come into view on chang- 

 ing the focus. The nuclei of the fat cells are pale oval bodies, with finely 

 granular chromatin (Fig. 60, n), often containing one or two small vacuoles. 

 The protoplasm around the nucleus forms such a thin layer that it is 

 scarcely appreciable on surface view. Both nucleus and protoplasm 

 are much darker when seen on edge, since a thicker layer of substance is 

 thus presented. When sectioned in this position the nuclei within the 

 cells must be carefully distinguished from those of the connective tissue 

 just outside. Many of the fat cells will show no nuclei, since the entire 

 cell is usually not included within the limits of one section. 



In extreme emaciation, the fat cells become small and the protoplasmic 

 rim thickens, so that the cells again assume the signet-ring form. A 



FIG. 60. NORMAL ADIPOSE TISSUE FROM AN ADULT. 



X 400. 

 Connective tissue is seen at the left of the figure and 



(as at c. t.) between the fat cells; n, nucleus 



of a fat cell. 



FIG. 61. FAT CELLS FROM THE OMENTUM IN A 



CASE OF EXTREME EMACIATION. X 520. 



b. v., blood vessel; f. c., fat cell. 



delicate reticulum appears between the shrunken cells as shown in Fig. 

 61. Some of the fibers proceed directly from the fat cells, indicating 

 that the processes have never wholly disappeared. Others come from 

 the fibroblasts which from the first are scattered among the fat cells. 



The great difference between the appearance of fresh fat cells and 

 those seen in sections is due to the fact that fat is dissolved by the reagents 

 ordinarily used in preserving the tissue. Thus the sections usually 

 show empty vacuoles and no fat whatever. Occasionally, as a result 

 of cooling, the fat has formed insoluble crystals in the shape of radiating 

 needles, and these, or an amorphous precipitate which takes a bluish 

 stain with haematoxylin, may be seen within the cells. Although fat 

 is the commonest substance to be found within the vacuoles in human 



