(169) have reviewed the many factors that may 

 result in adrenal enlargement. Infection generally 

 causes marked hypertrophy. A long-continued 

 stress ending in death results in marked hyper- 

 trophy and hyperplasia, with the degree of hyper- 

 trophy proportioned to the time which elapses 

 between the onset of stress and death. 



Summary. — In rats that were maintaining weight 

 when sacrificed, adrenal weights showed relatively 

 little variation with diet. The largest adrenals 

 were found in rats on the diet containing 25 per- 

 cent egg or consisting of 100 percent egg yolk. 

 Age also exerted little influence on adrenal size. 

 The relation of adrenal weight to body weight 

 varied significantly with diet. For any one diet, 

 adrenal size tended to parallel body weight but 

 the relatively low correlation coefficients for this 

 relationship indicated that the weight of this 

 organ was reflecting other factors as well. 



In rats that were losing weight, adrenals tended 

 to be large and no differences due to diet were 

 apparent when weight loss exceeded 100 grams. 

 When extensive kidney damage was present, 

 adrenals were generally large. The occasional 

 occurrence of large adrenals in rats with apparently 

 normal kidneys, however, suggests that adrenal 

 weights may be reflecting the general health of 

 the animal rather than a direct relation to kidney 

 damage. 



A comparison of the results of moribund Wistar 

 and BHE rats suggests a hereditary difference in 

 the response to stress, but provides no information 

 concerning possible differences in the weight of 

 this gland in normal healthy animals. 



Thyroid weight 



Rats maintaining weight on stock, SP 8 

 HVO, and SPE diets. — Data for the thyroid 

 weights of rats maintaining weight on stock, 

 SP 8 HVO, or SPE diets are summarized in table 

 44. The results for fasted and nonfasted rats 

 have been combined and the thyroid weights in 

 all cases include the parathyroids. On stock diet, 

 thyroid weights tended to increase with age up 

 to 700 days, but the differences were small con- 

 sidering the wide range of values observed for 

 any one age group. No large thyroids were 

 observed in animals over 700 days old, in contrast 

 to the relatively large adrenals from these same 

 rats. For rats fed SP 8 HVO diet, age appeared 

 to be without influence. The average of 11.8 

 mg. for the thyroid weights of animals fed this 

 diet was similar to the average of 11.1 for stock 

 rats, in spite of the large difference in the body 

 weights of these two groups. On SPE diet also, 

 age appeared to exert no consistent influence on 

 the size of this gland. The average weight of 

 16.2 mg. for the thyroids from rats fed SPE diet 

 was significantly more than the average for rats 

 fed either stock or SP 8 HVO diet (P<0.01). 



In table 45 are summarized data for thyroid 

 weights in relation to body weight. The range 

 of values for any one group was wide and cor- 

 relation coefficients were relatively low — -0.42, 

 0.46, and 0.31 for stock, SP 8 HVO, and SPE 

 diets, respectively. There was, however, a con- 

 sistent tendency for thyroid weights to increase 

 with body weight on all three diets, as evidenced 



Table 44. — Thyroid weights of rats maintaining weight at different ages on stock, SP 8 HVO, and SPE diets 





Rats 



Average 

 age 



Average 



body 



weight 



Thyroid weight 



Thyroids weighing — 



Diet and age of rats (days) 



Average 



Range 



Less 



than 



10.0 mg. 



10.0 to 

 14.9 mg. 



15.0 to 

 19.9 mg. 



20.0 mg. 

 and over 



Stock: 



Less than 200 . 



Number 

 19 

 24 

 13 

 13 

 12 

 12 

 8 



5 

 12 

 31 



7 

 9 



5 

 25 

 34 

 14 



9 



Days 

 151 

 249 

 381 

 449 

 538 

 652 

 844 



154 



250 

 337 

 457 

 550 



154 

 270 

 336 

 455 

 527 



Grams 

 390 

 454 

 452 

 475 

 493 

 468 

 468 



524 

 518 

 614 

 609 

 677 



524 

 599 

 616 

 621 

 637 



Mg. 

 9.7 



10. 2 



11. 2 



11. 9 



12. 6 

 12. 8 

 10. 4 



10. 5 

 10. 2 



12. 4 

 10. 1 



13. 8 



14. 5 



15. 



17. 8 

 13. 9 



18. 1 



Mg. 



6. 5-13. 3 

 5. 8-15. 7 



5. 6-15. 6 



7. 4-21. 7 

 9. 2-17. 



6. 0-16. 6 



7. 1-14. 9 



8. 5-12. 

 6. 6-18. 7 

 6. 7-17. 5 



6. 9-15. 7 



7. 8-19. 9 



11.9-17. 5 



9. 1-20. 8 

 10. 6-30. 4 



6. 1-20. 4 

 12. 3-23. 6 



Percent 

 63 

 42 

 31 

 23 

 8 

 25 

 40 



40 

 58 

 13 

 71 

 11 





 4 

 

 21 

 



Percent 

 37 

 54 

 54 

 62 

 75 

 42 

 60 



60 

 33 



74 

 14 

 44 



60 

 44 

 29 

 50 

 11 



Percent 







4 



15 



8 



17 



33 











8 

 13 

 14 



44 



40 

 48 

 47 

 21 

 56 



Percent 

 



200 to 299.. _ . 







300 to 399 



o 



400to499._. . 



8 



500 to 599 







600 to 699. . _ ..... 







700 and over 

 SP 8 HVO: 



Less than 200 _ . _ 





 



200to299._. 



o 



300 to 399 







400 to 499 



o 



500 to 599 .. 



o 



SPE: 



Less than 200. . 







200 to 299 . . 



4 



300 to 399 ._ . .. 



24 



400 to 499 . .. 



7 



500 to 599 



33 







57 



