CONNECTIVE TISSUES 



43 



membrane or cell wall. The nucleus is pushed to one side in this 

 process and is flattened against the cell membrane ; it is usually 

 embedded in a remnant of granular cytoplasm. Being thus dis- 

 tended with fluid fat, the cell acquires a spheroidal shape. 



During periods of starvation or malnutrition, at which time fat 

 decreases greatly in volume, many of the fat cells return to a con- 

 dition which approximates their former state. As the fat is 

 removed the cytoplasm of the cell increases in amount, but assumes 

 a peculiar fluid appearance and is not readily colored by the usual 

 dyes. These cells, which still contain a number of fat droplets, 

 are known as " serous " 

 fat cells. 



The origin of the fat 

 cell is still somewhat in 

 doubt. It was formerly 

 thought that it might 

 result from a deposit of 

 fat within any of the 

 connective tissue cells. 

 A second theory con- 

 siders that it arises only 

 from a special fat-forming 

 connective tissue cell. 

 The demonstration of 

 large numbers of peculiar 

 ovoid granular cells with- 

 in areas where fat cells 

 were undoubtedly form- 



FIG. 46. DEVELOPING ADIPOSE TISSUE FKOM THE 

 SUBCUTANEOUS TISSUE OF AN INFANT. 



The fat has been removed by immersion in alco- 

 hol and ether. The polygonal outlines of the fat 

 cells arc well shown. Within many of them is seen 

 the finer cytoplasmic network by which the inclosed 

 droplets of fat were invested ; this network had not 

 been completely replaced by the accumulation of fat. 

 Hematein and eosin. Photo, x 325. 



ing in fetal and young 



subjects, and the demonstration of similar cells in areas showing 

 fat formation in adult tissues, has lent support to the hypothesis 

 that these granular cells are the only progenitors of the fat cells 

 (Shaw *). 



Reticular Tissue (reticulated tissue, reticulum). Reticular tis- 

 sue occurs as the stroma of adenoid tissue in the lymphatic glands 

 and other lymphoid organs, and, according to Mall,f is also found 

 in the membrana propria of the secreting tubules of the stomach, 

 intestine, kidney, testis, and thyroid, and in the marrow of bone 

 and walls of the pulmonary air sacs. 



* J. Anat. and Physiol., 1901. 



f Johns Hop. Hosp. Rep., 1896. 



