Tar cancer in mice. 1, The technique of the comparative experiment / by A.F. Watson and E. Mellanby.

  • Watson, A. F.
Date:
[1930?]
Catalogue details

Licence: In copyright

Credit: Tar cancer in mice. 1, The technique of the comparative experiment / by A.F. Watson and E. Mellanby. Source: Wellcome Collection.

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    (4) The Occurrence of Metastatic Deposits in Other Organs and Tissues, more especially the Lungs, and the Incidence of Primary Epithelial Lung Tumours in the Animals of the Five Experimental Groups. Metastases to the primary skin-tumour occur frequently in mice tarred under the conditions described. They are found more especially in the adjacent lymph-nodes and in the lungs, and less frequently and at a later period of the experiment in the liver, spleen, heart, etc. Table Y shows the results of the examination of 257 tumour-bearing mice from the five groups of the experiment. For the purpose of the examinations, the organs of each animal were scrutinized by two observers at the time of autopsy. The lungs from each animal were again examined after they had been fixed in 10 % formol saline for 48 hours. This preliminary examination was followed up by a microscopical survey of sections of the skin at the site of tarring, of nodules of the lung, and of any tumour-like deposits in other organs and tissues. Table Y.—Summary of Post-mortem Examinations of Tumour-Bearing Mice Column. Group. l. Tota] numbers of tumour¬ bearing mice. 2. Presence of nodules in lung tissues. -A. Visibleatautopsy. 3. Presence of tumour like deposits in other organs. Visible at autopsy. Died. Killed. Examined. * No. % total. No. % total. No. % total. A 49 3 51 17 333 23 451 10 196 B 54 0 54 17 315 29 537 K D 9-3 C 39 5 42 11 26-2 21 500 3 7 1 D 56 0 54 18 333 30 55-6 8 14-8 F 57 1 56 20 35-7 32 574 11 196 Totals 255 9 257 83 32-7 . 135 524 37 144 # Of the 264 post-mortem examinations, the findings of 1 from Group A, 2 from C, 2 from D and 2 from F have not been included. The percentages of the animals with lung nodules distinguishable at autopsy varied in the different groups from 26'2 to 35'7, with an average for all mice of 32'7. The percentages of animals with tumour-like deposits distinguish¬ able at autopsy in organs other than the lungs varied in the five groups from 7'1 to 19'6, with an average for all mice of 14'4. It is obvious, therefore, that these nodules of the lungs are a more consistent feature of the post-mortem examinations than the cancerous deposits in other organs. After the fixation of the lung tissues in formol saline for 48 hours, many nodules which were indistinguishable before become readily recognizable to the naked eye. Thus the percentages of the animals with lung nodules which were visible to the naked eye after such fixation of the tissues varied in different groups of the present experiment from 45T to 57T, with an average for all mice of 52‘4. To summarize, nodules were distinguishable in the lungs of approximately one in every three tumour-bearing animals at post¬ mortem examination, and after fixation in formol saline, in the lungs of