THE TWO GREAT GROUPS OF CONNECTIVE-TISSUE CELLS. 27 



The oil confirms this and shows at once the great development and extent of fibroblasts whose 

 protoplasm about the nucleus and in all processes, many of which are long, is closely filled with 

 uniform-sized, refractive, pale-yellow, various-shaped vacuoles, among which and in frequent con- 

 nection with which are "thread" structures. These linear structures may in some cells be the pre- 

 dominant feature, the cell-body being rounded up and the "threads" lying in great numbers close 

 together, taking usually one general direction. The fibroblasts frequently (perhaps a quarter of all 

 cells) contain from 1 to 4 or 5 seed-shaped deep-blue bodies, evidently trypan-blue crystal remains. 



The macrophages are usually small round elements with medium-sized uniform vacuoles. Only 

 after much search are trypan-blue deposits (not infrequent in the fibroblasts) found, and then these 

 are single and minute. The vacuoles react somewhat more intensely with neutral red than the 

 fibroblast vacuoles. 



Films from the back (over erector spinse) show few fibroblasts with "threads." Occasionally 

 fibroblasts are found with red dye T 184 rodlets, and very rarely these are abundant. In such 

 cases they are sharply separate from the few trypan-blue deposits present. Dye T 148 rods are 

 almost always free from vacuoles, but all stages of their formation in vacuoles may be seen. They 

 are not present in macrophages. 



The skin of the scrotum contains the same types of deposits. "Threads" are not very 

 abundant. 



Protocol: Rat 43, injected intraperitoneal^ with a 0.1 per cent solution of trypan blue 

 March 4, 7, 10, 13, 16, 19, 22, 25, 28, 31, April 3, 7, 9, 13, and 15, 1 c. c. each day. 



April 18: Subcutaneous tissue of thigh examined. Animal is stainel a uniform light robin's egg 

 blue. Skin of thigh same color. Under the low-power, one sees chiefly bright-blue deposits in the 

 macrophages, but also trails of scantier and smaller deposits belonging to the fibroblasts can be made 

 out. At this power, however, the predominance of the macrophages is so marked as to give an 

 almost exclusive "macrophage reaction." 



Under the oil, macrophages contain many deep-blue crystals and dark or light blue angular 

 structures (distorted vacuoles). No true blue vacuoles are found. The crystals vary in their 

 length and thickness. In some cells they are very long and delicate. With neutral red there are 

 instances of round bodies in all the macrophages and an abundance of them in some few macro- 

 phages, but practically all of the trypan blue present is in the form of crystals, usually deep blue, 

 though light blue ones are present. 



The fibroblasts contain a scanty, but pretty constant, content of small angular deposits which 

 would be identified as minute crystals. The neutral red also shows a number of pale vermillion 

 linear and angular bodies identical in morphology with the blue ones, but invariably paler in blue 

 content. They range down to very small bodies, not much above the limit of visibility. They 

 are about as abundant in number as the deep-blue bodies, but the total of both structures does not 

 make any great number of deposits for these cells (fig. 53). 



Same animal injected with 0.5 per cent dye T 148, April 18, 0.5 c. c; April 19 to 28, 1 c. c« 

 each day. 



April SO: Autopsied. Animal is stained a plum color. Subcutaneous tissue is purple. Under 

 the low-power deep-blue deposits are seen in macrophages. The red deposits are so faint that little 

 of their nature can be made out. 



Under the oil, both types of cells are well laden with dye T 148 vacuoles. The fibroblasts 

 especially are filled with them. 



Macrophages carry deep-blue, sturdy, crystalline deposits which, while tending to occur in 

 pairs or forked, are not greatly influenced by the dye T 148. Crystals are found in vacuoles, on 

 searching, but in the majority of cells they are not inclosed in vacuoles, though these vacuoles (dye 

 T 148) are very abundant. Where the trypan-blue crystals are most numerous and long the dye 

 T 148 vacuoles are small. Trypan-blue crystals are usually substantial, but are occasionally more 

 needle-like, and in these instances the dye T 148 vacuoles are smaller (fig. 57). Near the puncture- 

 point some of the dye T 148 vacuoles attain greater size, and within these there are a number of 

 needles. The tendency to the formation of vacuoles about crystals is much more expressed on the 

 abdomen, and one finds here not infrequently cells with deep-blue vacuoles, however, not yet 

 perfectly spherical, and in which one or two crystals are still evident (fig. 54). This is more frequently 

 the case in the mesentery. 



Fibroblasts are packed with very uniform, fairly large vacuoles with a pale yellow color, 

 slightly refractive. A limited number of small, deep-blue crystals invariably occurs, and on com- 

 parison with the previous drawing it is evident that but a portion of the trypan-blue deposits seen 

 before are now detectable. Perhaps the majority of needles are inclosed in dye T 148 vacuoles, the 

 remainder being free (figs. 55, 50). 



