50 



MASS. EXPERIMENT STATION BULLETIN 391 



Table 25. — Distribution of Lesions in 384 Cases of Neoplasia Found in 



365 Chickens. 



Organs or Tissues 

 Involved 



E -5 



::: Bj ^ — 



•7- — O 



a E 



:£ nJ <Lj (u 



■f. S E E 

 o c c ^ 



E E 



n ni M o 



O XI -c 



(D 'Z. JZ 





Total Number 



of Cases 213 34 24 21 20 19 16 



Liver 116 1 7 16 19 2 



Kidney 108 21 8 9 3 



Gonad 112 10 13 



Spleen 93 12 19 



Peritoneum 64 6 12 6 



Blood 45 20 19 



Bone marrow 42 15*19 



Adrenal 62 1 4 



Intestine 42 2 5 3 1 



Lung 41 2 5 1 



Musculature 18 1 6 17 



Oviduct 3 34 



Pancreas 26 5 3 



Heart 24 1 2 



Skin and Subcutis .17 1 11 



Bursa of Fabricius. 24 



Proventriculus. ... 22 



Thymus 11 6 



Thyroid 10 1 5 



Parathyroid 4 1 8 



Upper respiratory 



tract 2 



Skull 2 



Miscellaneous It 



Nerves: 



Anterior 



Mesenteric. . . 50 4 



Brachial 47 



Lumbar 43 



Ischiadic 23 



Vagus 23 



of Remak 20 



It 



2 2 2 1111 



It 



*Examined in only 15 cases. 



tBrain. 



JDorsal root ganglia of thoracic nerve. 



^Tongue 



15.1 



13.1 



12.3 



6.8 



6.3 



5.5 



sideration. The characteristics of some types of neoplasia overlap so that dif- 

 ferentiation is difficult. Many tentative diagnoses based on macroscopic observa- 

 tions were considered questionable when made and were later found to be erron- 

 eous. Accurate identification of some cases of neoplasia from gross examination 

 is particularly difficult when the lesions differ considerably from those character- 

 istic for the tumcr. It is pertinent to mention that no attempt at correlation of 

 tentative and final diagnosis was made until the entire collection had been studied, 

 thereby eliminating the possibility of the earlier experience influencing the 

 tentative diagnoses made during the subsequent period of collection. This 

 experience would unquestionably lead to more accurate tentative diagnoses. 

 Several of the incorrect diagnoses appearing in the table were not actual errors 

 in interpretation, but were the result of concomitant tumors, the lesions cf which 

 were not given sufficiently serious consideration. In other instances, neoplasms 

 which were not suspected on macroscopic examination at the time of necropsy 

 were detected later by microscopic examination. This suggests that unrecog- 

 nized neoplasms may have been present in some birds considered negative for 



