44 



HISTOLOGY. 



which color the fat droplets red and demonstrate them even when minute. 

 In ordinary sections all the fat has been dissolved by treatment with alcohol, 

 Jeaving the protoplasmic rims 'enclosing empty spaces. The spaces, 

 however, correspond in size and shape with the droplets of fat which have 



Surface view of fat cells, in the nuclei of which fat droplets are visible. 



ue Blood vessel contain- 

 ing corpuscles. 



Fat cell and its nucleus in side view. Blood capillary. Connective tissue. 



FIG. 45. FAT TISSUE FROM THE HUMAN SCALP. 



been removed. Provided that the cells have not collapsed, they appear 

 as large, round or polygonal structures (Fig. 45). Some are seen in 

 surface view, as if looked down upon, and may show a broadly elliptical 

 nucleus containing perhaps one or two small vacuoles. Most of the cells 

 in thin sections are cut across. The protoplasmic rim, reduced to a line, 



may be seen to widen and enclose the nucleus, 

 but often no nucleus is found. This is because 

 the fat cells are so large that they may be cut 

 into several slices, only one of which carries 

 with it the nucleus. Filling the spaces between 

 the cells there is more or less connective tissue 

 containing blood vessels. The student should 

 distinguish the nuclei within the fat cells from 

 such connective tissue nuclei as may be closely 

 adjacent to them. In some sections, radiating 

 slender crystals, often ill denned, will be seen 

 within the fat vacuole. These are fat crystals 

 [margarin crystals] which formed as the fat 

 cooled and solidified; in the living body fat is fluid. 



All fat cells do not contain a single large vacuole. As described by 

 Dr. H. A. Christian there occur both at birth and in the adult such fat 



FIG. 46. FAT CELLS FROM NEAR 

 THE KIDNEY OF A NEW-BORX 

 CHILD. 



