FIG. 66.--37/11, Z-12, L. The same graft as shown in fig. 65 (preserved 48 hours after transplantation) Sector of right margin of graft drawn by higher magnification. Right side of figure tissues of host (black masses = fat); left side carcinomatous parenchyma; between them abundant spindle-cell tissue. Compare figs. 64 and 65. x. 500 in fig. 42. Several mitoses are seen in this tissue. In frozen sections, stained with sudan, we see a zone of large cells loaded with fat surrounding the necrotic mass, as already described above for other carcinomatous tumours: this fatty change appears in other places diffusely throughout the granulation-tissue. From the part of the tumour containing this cellular granulation-tissue and shown in fig. 63, minute fragments were picked out and inoculated for "early stage" examination. Examination of " Early Stages" of 11,Z, giving 12,L-In the periphery of the grafts preserved after 24 hours there are as in the previous generations many healthy stroma cells, although the greater number show degenerative changes. As usual all the fibrils are swollen and hyaline. In fig. 64 we have illustrated two different places of this 24 hours material, where mitoses are to be seen in cells which undoubtedly belong to the old stroma. By careful study of the corresponding places in serial sections behind and in front of these dividing cells, we have convinced ourselves that they cannot be explained as cells invading the graft from the host or isolated carcinoma cells. In 48 hours material we find a somewhat different picture to that of the previous generations. (1) In some places a broad zone of spindle cells surrounds the graft, and at first sight appears to be due to exaggerated fibroblast reaction, much more marked than we have seen it at so early a period in any other tumour. These appearances are shown in fig. 65, a low-power microphotograph of a graft after 48 hours; a portion of this is drawn at a higher magnification and given in fig. 66. (2) The number of healthy-looking cells belonging to the old stroma is greater than in the previous generations, where on the whole, they were very rare after 48 hours. In these grafts we also find cells surviving in the central parts of the graft, where the picture is not so much obscured by the new elements from the host, and for certain of these cells there is no evidence of their degeneration, but on the other hand we cannot prove that they are dividing. The cellular tissue round the graft suggests a pure reaction from the host. But on examining the grafts more closely, we hardly feel justified in maintaining this view The graft has been implanted into the fatty tissue, and the fat cells, clearly indicated as black masses (preserved in osmic acid) mark the limit of the tissues of the host. The large cells round the graft are all inside this border line, and there is a striking difference between the extremely cellular tissue immediately surrounding the graft and the tissues which with certainty can be said to belong to the host. The latter show only a very scanty reaction. The general impression of this picture is that there is no conclusive evidence of the cellular tissue round the graft being entirely derived from the surroundings as a reaction. On the other hand, we see in the 24 hours material (fig. 64), that stroma cells are dividing close to the margin of the graft. It is a natural suggestion that these cells dividing in the introduced graft might be the real source for the cellular tissue we find in 48 hours material. Moreover, the further observation of the daughter tumours derived from this same material gives us strong evidence that the latter supposition is the more probable, for, in the next generation there is no doubt that the stroma elements really survive and independently proliferate, as we shall show further on. The Series 12 L to which this material gave rise yielded a very low percentage; only one tumour was obtained out of 17 mice inoculated, i. e. 7 per cent. This tumour was operated upon nineteen days after. inoculation. As the preliminary examination of frozen sections showed remarkable changes in the stroma, the material removed was inoculated into 40 mice (series 13 Y), and in addition 30 mice were inoculated specially for "early stages." The removed tumour showed, in about one half of the section, the picture of an ordinary carcinoma with a somewhat increased amount of stroma in the central part. The other half is shown at a low magnification in fig. 67, and the centre again with a higher magnification in fig. 68. Between the carcinoma alveoli there have developed strands of a very cellular tissue consisting of large spindle shaped elements showing numerous mitoses. The carcinomatous alveoli seem to recede from the centre of the graft, so that it consists almost solely of spindle cell tissue with strong sclerotic fibres, intermingled with small necrotic areas. On examining this material in early stages we found that the majority of the large spindle cells remained alive, alongside of the carcinoma cells; but the fibres of the connective tissue are swollen and degenerated. Fig. 69 shows the appearance of this material 24 hours after inoculation. Numerous mitoses are to be seen in the large cells which have replaced the old stroma. Cells and nuclei of the most extraordinary sizes and shapes are met with, and pathological mitoses are frequently found. In the sarcomatous cells fine fibroglia fibres are present. The animal, in which a sarcomatous change could first be recognised definitely, was not sacrificed to obtain the material for inoculation. Its tumour was removed by operation, and then we re-inoculated the mouse in the left axilla with a pure carcinomatous tumour (18 E) in order to make quite sure, whether or not peculiarities of the connective tissue of this particular mouse had played a part in the appearance of the sarcoma. The second inoculation gave rise to a tumour and at the same time a huge recurrence developed in the right axilla. The mouse was killed 18 days after the second inoculation. The second tumour had then reached the size of a pea; microscopically it presents the usual picture of an adeno-carcinoma with extremely scanty Strain from second operation on 37/9 B. [To face p. 228. C B Microphoto, W. Imboden. FIG. 67.-37/12, L-13 Y. Tumour (19 days old) from third passage of this strain, directly descended from tumour of fig. 62 (figs. 61-63). Sarcomatous change similar to that in fig. 54. In the centre of the growth strands of large spindle-cells. Periphery to the top of FIG. 69.-37/12, L-13 Y. Same tumour as in figs. 68 and 69, examined in early stages. Graft, preserved 24 hours after transplantation. A tissues of host; B-cleft containing exudate; C=graft. The connective tissue cells of the graft show themselves capable of surviving transplantation and are dividing. Note size of connective tissue cells in this graft as compared with those of carcinomatous tumours (figs. 9 & 10). 500 Microphoto, W. Imboden. 100 UNIV |